Do Your Genes Determine Your Entire Life?

Whenever you read stories about identical twins separated at birth, they tend to follow the template set by the most remarkable of them all: the “two Jims”. James Springer and James Lewis were separated as one-month-olds, adopted by different families and reunited at age 39. When University of Minnesota psychologist Thomas Bouchard met them in 1979, he found, as a Washington Post article put it, both had “married and divorced a woman named Linda and remarried a Betty. They shared interests in mechanical drawing and carpentry; their favorite school subject had been maths, their least favorite, spelling. They smoked and drank the same amount and got headaches at the same time of day.” The similarities were uncanny. A great deal of who they would turn out to be appears to have been written in their genes.

Professor Tim Spector has been studying identical twins at King’s College London for more than 20 years. From the start of his research in the early 1990s, it became evident to Spector that identical twins were always more similar than brothers or sisters or non-identical twins. At the time, however, “social scientists hated the idea” that genes were an important determinant of who we were, “particularly in those rather controversial areas like IQ, personality and beliefs”. As “one of the many scientists who took the gene-centric view of the universe for granted”, Spector wanted “to prove them wrong, and to prove that there’s nothing that’s not genetic to some extent”. Today, he looks back on this as part of his “overzealous genetic phase”.

Who we are appears to be a product of both nature and nurture, in whatever proportion they contribute, and nothing else. You are shaped by forces beyond yourself, and do not choose what you become. And so when you go on to make the choices in life that really matter, you do so on the basis of beliefs, values and dispositions that you did not choose.

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