What Makes You Unique

Why did you choose to write about individuality? About four or five years ago I was single and looking to meet someone on OkCupid. As a scientist, you can't help but stand back and think about the scientific topics as you go through profiles or try to make yourself look good. I was there to meet someone, and I did - I found my wife there so it was a happy ending - but it also made me think about human individuality and what we know and don't about it . In the book you write, "A good phrase to replace the tired and imprecise" nature versus care "is the more complicated" inheritance that interacts with experience filtered by the inherent randomness of development. "What does this mean?

The phrase everyone knows, "nature vs. care" is so terrible and so wrong. The "vs." implies that what you inherit from your parents must be contrary to your experience in the world, which is not true. Often times these things interact. Take the genetic disease phenylketonuria, or PKU. You must inherit broken copies of a gene that metabolizes the amino acid phenylalanine from both parents. But it is only important if you are eating foods high in phenylalanine. If you never do, who cares? The word "parenting" makes people think too much about family, how your parents looked after you or didn't care about you. The experience that informs you as an individual is much broader. It's things like the food your mother ate when she carried you in her womb. Or the time of year you were born. Or the ambient temperature in the first year of your life.

The final problem is that one of the most important things is left out: pure, accidental happiness. Identical twins with the same DNA are not identical even at birth. They don't look identical, they don't have identical temperaments, and when you put them in medical scanners, their organs are not identical. Why is that? This is because the DNA doesn't tell exactly how we evolve in every connection between every specified cell. There is a vague set of instructions that randomness then acts on. Randomness is the cherry on top of the equation for hereditary interactions with experiences.
What is a surprising source of individual differences? When you are carried in the uterus and your mother fights off an infection, especially a viral infection, her body makes molecules called cytokines that are involved in the immune response. These molecules enter the fetus and the developing nervous system via the umbilical cord. There are receptors in the developing fetus' brain for those cytokines that affect development.

We know that mothers who fight infections while pregnant are at greater risk of developing schizophrenia and autism. From animal studies we have candidate molecules and molecular pathways that might be involved. The evidence from humans is mostly epidemiological evidence, but that will change in the years to come.

What is a common misconception about individuality? It turns out that when psychologists look closely at this, it just isn't true. Your birth order is an important determinant of your behavior and interaction in your own family, both as a child and as an adult. But it's not as if the first kids who tend to be the leaders in their families, the leaders in the playground at school, or the leaders of companies. It is not transmitted that way.

How should the science of individuality affect public order?. "That's just not true. None of the cognitive and behavioral traits known to us are produced by a gene or a small number of genes. They are created by many subtle variations that add up and interact. A recent study tried to identify the genes that are.