Dr. Cohen weaves together a rich tapestry of research in behavioral genetics to illustrate the degree to which biology, rather than parenting, can impact a child's personality, values, and aptitudes. Identical twins separated at birth are reunited in mid-life to discover that they both drive the same car, have held the same jobs, named their sons James, and married women with the same first name not once but twice. Yet siblings reared together in the same family environment often grow up to have very different interests, abilities, and beliefs. The nurture correlation between good parenting and child development fails to explain how, of two children raised in a loving and supportive home, one grows up to be a pillar of the community, while the other becomes a drug abuser. Parents have been blamed for problems ranging from antisocial behavior to autism to schizophrenia disorders which Dr. Cohen reveals have a strong genetic component. On the flip side, parents who weren't able to give their offspring a consistently safe and supportive home environment have happily taken the credit when their children grow up to be well-adjusted, hard-working members of society.
The truth of the matter is that, if sufficiently strong, inborn potentials can trump parental influence, no matter how positive or negative. Some traits manifest themselves in such unexpected and uncontrollable ways that, for better or for worse, one's child may indeed seem like a perfect stranger.