In Sigmund Freud’s psychology, John Watson’s behaviourism and Margaret Mead’s anthropology, nurture-determinism by parents was never tested, only ass… - Matt Ridley

Yet the evidence, from twin studies, from the children of immigrants and from adoption studies, is now staring us in the face: people get their personalities from their genes and from their peers, not from their parents.

Reproducing sexually must improve an individual’s reproductive success or else sex would not persist. It is increasingly hard to understand how human beings came to be so clever without considering sexual competition.

But the astonishing result (of IQ testing) is the correlation between the scores of adopted children reared together: zero. Being in the same family has no discernible effect on IQ at all.

In any case, no moral conclusions of any kind can be drawn from evolution.