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304 pages, Paperback
First published June 1, 2021
'What about twin studies?' said Hunter. 'Aren't they the gold standard for a lot of this genetic analysis?' `They're often treated that way,' said Olivia, 'but lots of clinical psychologists, like my brother Charlie, question the Equal Environment Assumption on which they rest. They attribute outcomes to purely genetic causes by ignoring favouritism, scapegoating, imposed narratives and, in the case of identical twins, the effects of often being dressed in the same clothes, being in the same class at school, having the same friends, being mistaken for each other and experiencing "ego fusion". Genetic enthusiasts try to get around these social and psychological facts by saying that the genes of identical twins "create" confounding non-genetic influences, as if two infant twins, lying next to each other in the same pram, cast out a powerful genetic force field that compels their mother to dress them identically, while the rest of the world turns to stone. The mother herself is not, in this persuasive scenario, subject to any environmental, financial, social or psychological forces, or indeed genetic influences of her own, but is just controlled by her monozygotic twins' genetic "creativity". It's the kind of circular argument, assuming what it set out to prove, that appears again and again in twin studies, like a wagon formation protecting a beleaguered dogma.