The environment that a child experiences is as much a consequence of the child's genes as it is of external factors: the child seeks out and creates his or her own environment. If she is of a mechanical bent, she practises mechanical skills; if a bookworm, she seeks out books. The genes may create an appetite, not an aptitude. After all, the high heritability of short-sightedness is accounted for not just by the heritability of eye shape, but by the heritability of literate habits. The heritability of intelligence may therefore be about the genetics of nurture, just as much as the genetics of nature. What a richly satisfying end to the century of argument inaugurated by Galton.