Geoffrey MillerVerified account

4/ I esp liked his point that nurture often reinforces, doesn't counter, nature. If you have some innate traits that make you an unlikeable baby, people's reactions to you may reinforce that. If you have some innate traits that make more likely to be good at school, people's

5/ positive reactions will reinforce those traits, incl/by physically changing the brain. Great point I'd not considered. I also liked his point that bigger brain regions in some people (or sexes) may not mean "better" - might mean "less efficient so must be bigger to be as good"

6/ There were some times when I thought it could have used another hard edit to make it more internally consistent. He early stresses importance of regulatory DNA but later talks of mutations only being important if they are in the "3%" of important DNA. I know he knows better.

7/ Similarly he focuses more on DNA as the book goes on. He stresses early that chance in development (say 70/30 odds on neurons going the right place) are important but later proclaims all mental illness is genetic (before qualifying that a bit late in that chapter).

8/ Then there are things I wish he had discussed more. I'd love more discussion than I recall in the book about mosaicism, esp the apparently high level of it in brain neurons, And I wish he had paid a bit more attention to pleiotropy. He considers it at points but not always.

9/ (I think.) E.g., he says small IQ boosting alleles are likely to be fixed in pops but IQ lowering ones won't be but should be under selection pressure. But what if IQ+ has, in some environments (external or genetic) non IQ effects that outweigh their benefits (& vice versa)

10/ I do have another IQ question. He argues strongly that it is largely innate & heavily genetic. But he does discuss the Flynn effect (pop mean IQs increasing over time). And he has an eg that makes this descendant of East Galway (Mc)Grealy's happy - the Irish.

This is a great question and a subtle point. IQ is highly *heritable* within a given population (much of the variance is genetic in origin). But heritability only tells you what *does* vary and affect a trait, not what *could*...