Identically Different: Why We Can Change Our Genes

by Tim Spector

How much are the things you choose to do everyday--what you eat, how you vote, who you love--determined by your genes, and how much is your own free will? Using fascinating case studies of identical twins, leading geneticist Tim Spector explains how even real-life "clones" with the same upbringing turn out in reality to be very different. Drawing on his own cutting-edge research in genetics, Spector show us that nothing is completely hard-wired or pre-ordained. Challenging, enlightening and entertaining, Identically Different explores topics as varied as why the Dutch have become the tallest nation in the world, why autism is more heritable than breast cancer, and what could cause a healthy man to have a heart attack within weeks of his overweight, heavy smoking identical twin. Spector's probing and thoughtful study helps us to understand what makes each of us so unique.

Genres: Science, Nonfiction, Health, Biology, Genetics, Psychology, Medicine

288 pages, Hardcover

First published January 1, 2012

About the author

Tim Spector is Professor of Genetic Epidemiology at Kings College, London and Director of the TwinsUK Registry, which is one of the worlds richest data collections on 11,000 twins. He trained as a physician with a career in research, which since 1992 has demonstrated the genetic basis of a wide range of common diseases, previously thought to be mainly due to ageing and environment. Most recently his group have found over 400 novel genes in over 30 diseases, such as osteoporosis, osteoarthritis, melanoma, baldness, and longevity. He has published over 600 research articles in prestigious journals including Science and Nature. He coordinates many worldwide genetic consortia and is currently at the forefront of research with a highly competitive European Research Council Senior Investigator award to study Epigenetics – a new exciting research area into how genes can be altered. He is the author of several books for the scientific and public communities and presents regularly in the media.

Reviews

[Nicky · Rating 4 out of 5]

I wasn't sure how this would turn out, since it mentions the widely ridiculed Lamarckian theory of inheritance, and the subtitle "Why You Can Change Your Genes" might sound a tad self-helpy. Luckily, it is actually a sound examination of current epigenetic theory, based on MZ and DZ twin studies looking at heritability. It makes an excellent follow-up to James Watson's DNA, in that it moves on from the gene-centric view of biology to the more nuanced ideas we have now.

I've always been fascinated by epigenetics. The whole idea is what made me interested in potentially becoming a geneticist: the idea that Lamarck wasn't entirely wrong, that events within a person's life can be passed on to their children and grandchildren. (The famous giraffe neck example was unequivocally wrong, however.) The example given then, and raised in this book, is that of potential epigenetic changes caused by IVF treatments, and the general lower health of children conceived via IVF.

What really fascinates me now is that maybe my anxiety issues are related to the methylation of some of my DNA, preventing transcription of some proteins. And that would probably be a self-feeding process, with stress causing the original methylation and then decreased availability of a particular neurotransmitter causes more anxiety (less ability to regulate emotion) and more stress. If I could only remove those methyl groups from my brain cells, I could stop taking my medication and get on with my life. If I could magically go into research right now, that is undoubtedly where I'd go.

The book covers a lot of different topics -- sexuality, gender identity, athletic ability, talent, religious belief -- and manages to do so without stepping on too many toes, to my mind. It presents a much less deterministic version of genetics and the epigenome than Watson's DNA does, which people may find more palatable.

It was basically the sort of book where I spent a lot of time texting people saying "did you know...?" I found it an easy read, and it has copious amounts of footnotes and opportunities to do further reading. Another one I heartily recommend!

[Kat Peterson · Rating 2 out of 5]

I appreciated this book for the data, but found many of Tim Spector's social ideas to be outdated, and some of his medical knowledge to be off.

For example, he wonders about the "G-spot" and if all women have it. The G-spot is a part of the clitoris so yes, all those who have a clitoris have it. He also wonders about the "usefulness" of the female orgasm and arousal, and if it will "stick around or disappear, evolutionarily". I find his thoughts about this to be uneducated and not based in science about the female body and the role arousal plays. I also found he did not consider many social factors that contribute to how different genders are socialized about sexuality.

He also likens autism to "a lack of empathy" which he does not explicitly define. Not all autistic people experience a "lack of empathy", and for those who do- I find it very important to note that this does NOT mean they lack compassion (the ability to care for others and have concern for their suffering.) I found the way he painted autism to be disappointing and uneducated.

Also, the way he discussed abuse and it's effects: there were many factors he "wonders" about, which he should not be wondering about. There is plenty of social science and evidence out there to support or contradict his data, but he chooses instead to remain fairly neutral and "speculative" on topics that I would personally find inherently not-neutral (such as incest and child abuse and it's effect on the individual.)

In addition, he makes jokes about homosexuality I found inappropriate.

His data is great and solid, but I was disappointed in his lack of balance when it came to objective data vs. social psychology and physiology.

[Mark · Rating 3 out of 5]

Tim Spector is a UK scientist who studies twins, particularly to explore what traits are inherited and which are not. He uses this as an entree into the field of epigenetics, which looks at how environmental and other influences change the way a genome functions without actually changing or mutating the DNA itself.

To make this book more appealing, I surmise, he broke it down into different human traits like violence, obesity, parenting and sexual orientation, and in each chapter he tells the stories of identical twins who ended up being quite different on these various scales.

The trouble I had with the book is that despite this attempt at systematic organization, each chapter felt as though it were rambling around, particularly in trying to summarize the huge body of research he footnotes in the back. And to be fair, he is handicapped by the fact that the biology and causative mechanisms of epigenetics are still being discovered, and so his book is a little ahead of the curve.

The book did come together better more toward the end, in his chapters on sexual response and orientation, and the bacterial community we all inherit inside our bodies.

For giving us a lot to think about, I'll give this an A. For execution, a B-.

(Oh, and BTW, as with so many books today, the subtitle is a fraud: this book in no way tells you how you can change your genes)

[gretafasurf ☆ · Rating 4 out of 5]

Scrivo questa recensione a seguito di una piacevole rilettura di questo libro, che personalmente ho affrontato con più interesse (e più consapevolezza) rispetto alla prima volta ormai due anni fa, e che mi ha permesso di muovere un microscopico passo in più verso un mondo che da sempre mi affascina parecchio: la genetica.
Questo saggio tratta soprattutto di epigenetica, analizzando in particolare le analogie e le differenze che persistono nei comportamenti, nei gusti, nelle tendenze e propensioni sia caratteriali che patologiche tra gemelli - sia omozigoti che eterozigoti - che per qualsivoglia istanza abbiano trascorso una parte fondamentale del loro vissuto conducendo esistenze profondamente diverse, in ambienti spesso diametralmente opposti.
Queste condizioni su larga scala sono fondamentali per comprendere quanto l'ambiente e quindi la "cultura" influenzi il nostro codice genetico e quindi la "natura".
Grazie a questi esperimenti comprovati da studi, statistiche e dati reali e rintracciabili nelle note del testo, Tim Spector ci presenta una biologia molto diversa da quella che siamo abituati a studiare a scuola.
Non sempre questo ramo di studi fu apprezzato dall'opinione pubblica, perché spesso le verità genetiche si presentano talmente in contrasto con le convinzioni popolari e l'etica della maggioranza delle persone che è difficile scenderci a compromessi.
Si tratta di un'area contemporanea della biologia, fortemente in espansione nei più recenti decenni ma ancora tutta da esplorare, che risponde - o almeno ci prova - a numerosi interrogativi anche parecchio filosofici: cosa spinge l'uomo a credere in Dio? Quali fattori determinano la sua sessualità? e via discorrendo...
Lo stile è semplice e colloquiale, si serve di terminologia specifica solo ai fini della divulgazione spiegando la maggior parte dei termini utilizzati.
La maggioranza delle nozioni base di ereditarietà viene data per scontata quindi consiglio questa lettura a chi ha già familiarità con la genetica e il suo mondo sconfinato, o almeno con una minima parte di esso, ma che vuole esplorarlo in una nuova chiave contemporanea, per sentirsi parte integrante di una scienza influente nelle nostre vite a 360 gradi, che ogni giorno si evolve, si trasforma e realizza sempre nuove e innovative ipotesi pronte a stimolare la nostra curiosità.

[Leo · Rating 5 out of 5]

Best pop-science book I've read in ages. Cutting edge research presented in a witty and accessible way. Has genuinely changed the way I think about life, inheritance and evolution. Can't recommend it enough.

[Margaret · Rating 3 out of 5]

An interesting book on how our genes aren't as fixed as scientists have long thought they were.

Interesting, but not as much as his other book "The Diet Myth".

Recommended for the scientifically minded.

[Dawn With-whippet · Rating 3 out of 5]

written in 2012 and as this is a book about genetics it shows its age . There have been so many advances in this field over the past 12 years so it was bound to be a little dated . The chapter on Autism is particularly grating . There is an interesting chapter on the role of gut bacteria on human health and behaviour which obviously the author has now focused on and developed with his Zoe app
Theres a whole chapter on the Gspot and female orgasm with some rather suspect experiments on female twins
Interesting as a historic medical viewpoint and great warning to medics that we can't ever be sure that we are correct in our understanding of the complexities of the human mind and body . Time will always bring new understanding

[The · Rating 1 out of 5]

DNF

[Mel · Rating 4 out of 5]

I'm not a biologist so it's difficult to critique a book that is outside my expertise. However, I found myself feeling a little sceptical of some of this content to the point I had to go and double check who Tim Spector is and how reputable he is.

My caution may have been down to Spector's tendency to go off topic and make unrelated, dare I say even, uneducated comments about things such as autism or female sexuality (topics I actually do have expertise in), or perhaps because the book is now 12 years old and science has moved on a lot in over a decade.

However, I'm giving it 4 stars because I found it easy to get through and because of the huge number of interesting case studies given. Even though I wasn't entirely satisfied with Spector's delivery, I still found the subject exploration fascinating and learned a lot.

[Kate Robinson · Rating 3 out of 5]

I enjoyed this book and learn a few things about epigenetics, the influence of nature vs nurture and the affect of your choices on generations to come that I previously had never even thought about. The book walks a fine line between too much information for someone without a background in biology to perhaps too little information in some areas. Overall though a interesting read but probably not one I would recommend.

[Karanja Mose · Rating 5 out of 5]

"Essentially, epigenetics is the mechanism by which environmental changes alter the behaviour of our genes," he says. "This involves a process known as methylation, which occurs when a chemical known as methyl, which floats around the inside of our cells, attaches itself to our DNA. When it does so, it can inhibit or turn down the activity of a gene and block it from making a particular version of a protein in our bodies." Crucially, all sorts of life events can affect DNA methylation levels in our bodies: diet, illnesses, ageing, chemicals in the environment, smoking, drugs and medicines."

[Steve Bennett · Rating 5 out of 5]

I read this after quite a few other of the books that Tim Spector refers too and coincidentally while on holiday with friends who have non-identical twins. I learned a lot that was new to me namely epigenetics which helped me make more sense of what is apparent but anecdotal about my own life experiences and the differences you see between people I know who are related. A fascinating, insightful and scientific read that in places made me laugh out loud.

[James · Rating 1 out of 5]

This was an annoying book to read.

The author has no talent for writing and constantly says silly or stupid things.

It's like his brain doesn't have a filter on it,
and he talks like a hyperactive 6 year old.

On page 70 he says: "a wave of best selling books...
have all provided the same clear message"

As if what a bunch of pop writers say
is scientific proof of something.

[Elentarri · Rating 2 out of 5]

A gene for this, a gene for that, add in a whole stack of twins, with epigenetics playing peek-a-boo..... and you have a rather dull book. This book might be more interesting if you aren't familiar with genetics, but if you are, then there is nothing new here. If you are looking for a more detailed book on epigenetics, look elsewhere.

[Natalie Rosser · Rating 2 out of 5]

The conclusion of every chapter (whether he was looking at sport or religion) is the same - your phenotype is influenced by both nature and nurture. Isn't that what we've always known? There were no revolutionary findings, and I got bored of this book towards the end and didn't finish it.

[Richard · Rating 5 out of 5]

Well-written, concise overview of what's known about epigenetics and "Fat Genes", "Gay Genes", "Infidelity Genes", "Bacteria Genes" and more.

[William Rawson · Rating 4 out of 5]

Tim Spector is a research physician by training, and is now a Professor of Genetic Epidemiology at Kings College, London as well as the founder of TwinsUK. He has a long history of research in the field of genetics and has been awarded the European Research Council Senior Investigator award which charges him with the study of relatively new field of epigenetics He has presented at least two TED talks, although it is my opinion that his skill with a pen far outweighs his public speaking finesse.
Identically Different is an interesting book that explores the underlying genetic contribution towards many human traits, some previously thought to be entirely genetically controlled and others presumed to have nothing whatsoever to do with genetic influence, by comparing people who are genetic clones of one another: identical twins.
The book is comprised of a preface, introduction, and thirteen chapters, followed by acknowledgements, notes and a useful index. There are no illustrations or photographs and, while I understand the rationale of protecting the identities of some of the pairs of twins involved, I feel the experience was poorer for it.
The ‘notes’ section could have been called ‘references’ as the vast majority of it was dedicated to referencing the studies he had cited, which was rather a disappointment to discover. I enjoy the use of footnotes to enrich the context of a text, but just being redirected to other authors and titles was not as rewarding an experience.
The book’s chapters are each fairly self-contained units, dealing with a specific aspect of how genes relate to a popular culture topic. “The fat gene”, “The gay gene”, “The fidelity gene”, to name but a few. In each chapter Spector discusses our cultural perceptions and expectations and contrasts them with what has actually been found in the numerous twin studies conducted all around the world. Some of the results are highly controversial and quite surprising, especially when it comes to his findings on the negligible value of good parenting, the genetic tendency of an individual towards being religious, and the lack of psychological damage resulting from what amounts to “consensual” cases of paedophilia.
Within each of his chapters he relates many personal anecdotes of his own studies and encounters and his experiences in running a reality TV show and consulting to the media. He often stresses that the media’s favourite portrayal of twins as almost supernaturally connected is very far from the truth, and that the press have actively sought the fringe cases to preserve this public image. Most identical twins vary significantly in their personalities, and moderately in their looks, and this is exactly why he focuses his work on them. Why would people with exactly the same genetic code express such a distinct variety of physical and psychological differences? The answer, quite unsurprisingly, is epigenetics: the ability of our experiences (and those of our ancestors) to alter the way our DNA expresses itself.
As Tim explains, DNA and the effect of genes on our personalities and bodies is far more complex than we first imagined. We initially posited that single genes coded for single characteristics, but have found this to be a simplistic interpretation, with some characteristics being effected by more than 30 known genes and their interactions with one another. As has been seen in the pet cloning industry, identical clones of the same cat can have completely different fur patterns based on ‘random’ genetic recombinations.
Tim’s writing style is casual and jovial, with very accessible language and many jokes interspersed within the body of the text. His anecdotes are interesting and fun to read over and he connects them well to his topics in most cases.
With epigenetics playing a more central role in our understanding of both physical and psychological health going forward, and being a topical and controversial subject of news and conversation at the moment, I would recommend this book to anyone who has an interest in genes and our ability to modify their expression as a starting point into possibly a more expansive exploration of the topic. As the chapters are stand-alone it can also be a source of useful examples and anecdotes to share with other interested parties.
Less practically, if you wonder about our future in terms of being able to predict and manipulate the exact characteristic of children before they are born and the potential to “order” and “tailor make” a child to prescribed specifications, this book will lend you some interesting insights into whether or not those science fiction movies could become documentaries one day.

[Ana Pereira · Rating 5 out of 5]

RESUMO DO LIVRO ESCRITO EM 2012:
Sendo o segundo livro do autor, é contudo o primeiro em que se afasta do determinismo genético. Especialista em epidemiologia genética, estudou gémeos durante anos no Reino Unido com financiamento da União Europeia. Mas mesmo gémeos são «identicamente distintos».

Os genes determinam o nosso aspeto e anatomia, e, em grande medida, a maioria dos nossos gestos inconscientes, como a maneira de rir ou de beber com uma chávena. Somos muito recetivos a pistas subtis na linguagem corporal, por isso, os estranhos pensam que os gémeos têm parenças arrepiantes. Mas o aspeto e os gestos superficiais turvam-nos a vista, existindo diferenças consideráveis entre gémeos.

São os genes que garantem a nossa flexibilidade e aleatoriedade (os genes da plasticidade), são eles que talvez nos estejam a proteger de uma forma subtil, pois asseguram que as caraterísticas de cada geração sejam mais variadas e imprevisíveis quando são expostas a ambientes que mudam. Esta variabilidade é fundamental para a sobrevivência humana. Sem ela, responderíamos do mesmo modo e poderíamos morrer todos face à fome, epidemias, gula e desastres naturais.

Muita coisa falta ainda compreender na área da epigenética, mas quatro crenças foram derrubadas. A 1.ª crença: os genes são a essência dos seres humanos, o nosso padrão ou o código da vida.
O uso frequente e infalível dos genes nas ciências forenses contribuiu para lhes dar uma reputação exagerada, assim como a influência de autores como Richard Dawkins (escreveu o Gene Egoísta) que propôs que que os seres humanos não eram senão os portadores quase robóticos destes genes «egoístas» e autoreplicantes.
Os genes não deixam de ser importantes, mas perderam o seu estatuto privilegiado e proeminente, em especial porque está a desaparecer a distinção entre inato e adquirido (nature versus nurture).
Os genes são atores importantes do corpo, mas não podem atuar sozinhos e formam parte de uma equipa complexa. A célula que os hospede é também importante, pois produz as proteínas e enzimas que levam a cabo as funções corporais e outros processos fundamentais, inclusive a ativação e desativação de genes, como os efeitos epigenéticos a longo prazo como a metilação.
Somos organismos complexos formados por redes de células em interação, o que inclui os genes, os sistemas que modificam os genes, a sua expresão e a forma como trabalham uns com os outros.
Além disso, as leis que regem tudo isto não são rígidas, daí que não há pré-determinação, ou seja, não estamos predestinados pelos nossos genes. Assim, do mesmo modo que podemos mudar o nosso estilo de vida, também podemos mudar os nossos genes.

A 2ª crença errónea: os genes e o destino herdado era fixo. Agora sabe-se que isto é a exceção, não a regra. Isto acontece apenas em doenças raras, como a de Huntington, em que a mutação de um único gene provoca demência precoce e morte. No entanto, mesmo no caso desta doença, não podemos prever de forma exata qual será a gravidade e em que altura aparecem os sintomas.

A 4ª crença: Os efeitos do meio dos pais ou dos avós não podem transmitir-se. É isto a hereditariedade de carateres adquiridos ou soft inherance que Lamarck propõe e Darwin aceitou como sendo possível. Os efeitos da grande fome nos Países Baixos na 2ª Guerra Mundial transmitiram-se aos filhos, o que acontece tanto nos seres humanos como nos outros mamíferos. É um mecanismo epigenético.

Resumo: A lição mais importante é que podemos mudar os nossos genes, o nosso destino e o dos nossos filhos e netos. Importa, e muito, o que fazemos ao nosso corpo, e importa também o que os nossos avós fizeram aos seus há muitos anos. Talvez tenham enfrentado situações de stress como a fome e doenças, mas nós também temos de enfrentar decisões vitais como deixar de fumar, tornar-mo-nos vegetarianos ou mudar a nossa flora intestinal. Estas decisões podem afetar a nossa vida e, possivelmente, a de várias gerações.

[John Findlay · Rating 5 out of 5]

I am probably the perfect audience for this book. I have recently become a grandfather to identical twin boys, and through my work I have studied epigenetics, particularly DNA methylation, for many years. Therefore I think my 5-star rating may be biased. I am not sure that all readers will enjoy the book as much as I did, particularly those without as much of a genetics background. Portions of it may get too technical for some people (and not technical enough for others who are well-versed in the field). Spector had to walk a fine line. Despite my background, I learned a ton. The bottom-line message is to not expect your identical twins to be identical, and to treat them as the individuals that they are. In chapter after chapter, dealing with issues such as cancer, sexuality, fatness, fidelity, happiness, mortality, and talent, Spector makes the case that our fates are not just determined by our genes and the environment we encounter, but also by epigenetic effects (due to the environment) that can also be inherited. I had never realized that what your grandparents had been exposed to might effect your own life, but, in fact, epigenetic effects can be inherited across generations. And this field is still evolving, and new effects will likely be discovered. So identical twins will have essentially the same DNA, but they will have different epigenetic modifications of that DNA, and will experience different environments themselves. All of these determinants will play a role in the person that they become. Personalities can be different. One twin may be gay while another is straight. And the list goes on and on, with Spector providing examples. I must admit that it can be confusing at times, and that there appear to be contradictions, but that is the nature of science. I think that many people, but not all, will enjoy reading this book (and keeping up with the research of Spector and others). It helps if you have identical twin relatives, or if you are interested in the growing field of epigenetics.

[Gustavo HdzMry · Rating 2 out of 5]

Spector is a renowned researcher who works with twins. Identical twins are a type of natural experiment that helps separate the genetic and non-genetic determinants of a particular biological process. Social scientists have also used this approach. The literature established the debate between nature and nurture, however, Spector argues that there is a third element missing from the equation: the epigenetic factor. The traditional dichotomy, he says, is useless because of the growing evidence of epigenetic effects. In this regard, I expected an explanation of the specific mechanisms through which epigenetics work. Instead, I found a myriad of very interesting examples, although the epigenetic factor resembles a black box. That is, the author argues that what heritability cannot explain is PROBABLY attributable to epigenetics. While heritability is quite measurable, epigenetics seems to be a measure of what is ignored. This may not be true of all cases (you should read the papers cited), but there are only a few clear explanations in the book about how an epigenetic effect is correctly identified, such as studying clones or accounting for the role of parents in the attributes of male offspring. Another weakness of the book is that each chapter, ranging from intelligence to mortality, basically reaches the same conclusion you already know from the introduction: epigenetics can explain what genes alone cannot. Besides, a progressive development of chapters is absent. It doesn't matter what chapter you're reading, each one is mostly independent from the other. However, the "Did you know that?"-examples keep you reading. Certainly, the chapter on the heritability of the intestinal flora was very interesting for me. Overall, it's a good read that depends on what you're looking for specifically.

[Mariam Lami · Rating 3 out of 5]

Interesting to get an understanding of the nature/nature arguments of many personality traits such as infidelity and being religious. Also good twin stories from Spector’s research too.

This book is just basically everything going on in genetics research as a broad overview but slightly outdated given it was written in 2012. I prefer more expert detail in a specific subject rather than the cobbling of information and opinions in a vast and complex field that this book I feel does.

It has just left me realising that there is such a complex interplay between environment and genes that we will probably only find correlations but never causation for why people are different to others or have certain traits.

[Aude · Rating 3 out of 5]

An interesting book about epigenetics. To fully appreciate it the reader would probably benefit from some familiarity with the topic. I liked the mix of data, scientific studies and personal stories, otherwise the book would have been too dry. In the same genre and concerning the debate on nature versus nature, but more engrossing, moving and thought-provoking in my view, was Far From The Tree. But for an overall picture of where things stood on genetics/epigenetics a few years ago this was quite good.

[Michelle · Rating 4 out of 5]

Some parts are a little bit outdated now but the material is interesting and inspirational although it doesn’t necessarily try to be inspirational. Fact-based and research oriented and overall suggests that we can control far less than we think we can… but not exactly in the way that we expect. The topics explored are all really fascinating- from heritability of various physical and mental diseases to differences between us such as religiosity and sexual orientation and violence and talent, this book is more than worth the read!

[Soichiro Saeki · Rating 4 out of 5]

双生児研究は日本では医学的な分野では大阪大学、社会、心理学的な分野では慶應義塾大学が中心となって行われていますが、本著に紹介されるほど大規模な調査は現在行うことができていないのが現状です。
本著で紹介される研究成果は主に欧米人に関する記述であり、遺伝的にも環境的にも世界的に見ると特殊な日本人には必ずしも全てが当てはまるわけではないという観点もまず大事かと思います。

そのような前提の上で、本著は主にふたごの特徴に注目しながら、最近研究分野としてはホットな「エピジェネティクス」の解説がわかりやすくなされています。著者がお医者さんであり研究者でもいらっしゃる事もあり、その辺りの記述は正確であるように感じました。いい勉強になります。また、「環境」という要因を対比して「遺伝」を捉えることにより、遺伝学のコンセプトがよく捉えやすくなるかと思います。


ただ、西欧特有のジョークで若干ブラックすぎるような点があるように感じたのも事実…

[Kate Jenner · Rating 4 out of 5]

A really fascinating read about epigenetics. It really makes you realise how much we still have to learn about our genes and microbiome. I felt it was also really well balanced between explaining science to non-specialists without dumbing it down or patronising the reader. I would definitely recommend this book to anyone with an interest in human development and disease.

[Nicole · Rating 4 out of 5]

really enjoyable read, with many interesting stories about twins and some funny quips. the book is a little all over the place, so nothing is in too much detail (good for a casual read, but not very scientifically informative). He does round off everything quite well in the last chapter which is nice.

[Kathleen · Rating 5 out of 5]

Among other things, I learned it's not weird that my twins have different tastes in chocolate; that's "nurture."

[Julie · Rating 3 out of 5]

Really great info. Was expecting more scientific discussion on epigenetics. But still very interesting and instructional.

[Austin Daigle · Rating 4 out of 5]

I enjoyed reading about all the twin studies and potential applications of this exciting new field. The book raised a lot more questions than answers for me. The author’s personal opinions injected throughout the book seemed irrelevant or misleading at times.

[Ian Lea · Rating 4 out of 5]

Another, earlier, good book by Mr Spector whose The Diet Myth I read recently. He's not the best writer in the world but gets on with it, always interesting and informative.