Twins And What They Tell Us About Who We Are

Twins
And What They Tell Us About Who We Are
By LAWRENCE WRIGHT



This argument has been raging for centuries, with science entering evidence on either side and public opinion shifting in response. Using twins, and also data derived from adoption studies, scientists can now estimate what proportion of the variation in our intelligence, our personality, our behavior, and even seemingly random life events such as bankruptcy or the death of a spouse, might be caused by inherited tendencies. The broad movement from environmentalism to genetic determinism that has occurred in psychology over the last thirty years has foreshadowed the increasingly popular belief that people are genetically programmed to become the way they are, and therefore little can be done, in the way of changing the environment, that will make an appreciable difference in improving test scores or lowering crime rates or reducing poverty, to name several conspicuous examples.


Wright claims that the ''most surprising and important discovery'' of behavioral genetics is that one's family environment has ''essentially no effect on the development of personality,''


he concedes that the family makes a big difference in a child's level of ''positive emotionality,'' and that ''the one thing a good family can do is to make a child happy.'' Elsewhere, we are told that parents also influence a child's level of self-esteem and motivation. Hence, the degree to which you are persuaded that the ''family makes no difference'' in personality formation hinges on the degree to which you think happiness and self-confidence are core features of personality or mere bells and whistles.


I know of two cases in which television producers tried to do documentaries about identical twins reared apart, but then found the twins so distinctive in personal style -- one talky and outgoing, the other shy and insecure -- that the shows collapsed of their own unpersuasiveness.


Wright notes that ''there has simply been nothing on the environmental side to counter the power of twin and adoption studies,'' and the complaint is accurate enough. Until Einstein came along, nobody had a good alternative to cosmic ether, either. Sometimes a confession of ignorance is the only defensible stand.