“Identical twins think and feel in such similar ways that they sometimes
suspect they are linked by telepathy. When separated at birth and reunited as
adults, they say they feel they have known each other all their lives. Testing
confirms that identical twins, whether separated at birth or not, are eerily alike
(though far from identical) in just about any trait one can measure. They are
similar in verbal, mathematical, and general intelligence, in their degree of life
satisfaction, and in personality traits such as introversion, agreeableness, neuroticism,
conscientiousness, and openness to experience. They have similar attitudes
toward controversial issues such as the death penalty, religion, and
modern music. They resemble each other not just in paper-and-pencil tests
but in consequential behavior such as gambling, divorcing, committing
crimes, getting into accidents, and watching television. And they boast dozens
of shared idiosyncrasies such as giggling incessantly, giving interminable answers
to simple questions, dipping buttered toast in coffee,and-in the case of
Abigail van Buren and Ann Landers-writing indistinguishable syndicated
advice columns. The crags and valleysof their electroencephalograms (brainwaves)
are as alike as those of a single person recorded on two occasions, and
the wrinkles of their brains and distribution of gray matter across cortical
areas are also similar.”