[tweedledee]

You’re talking about phenotypes. With height people with entirely the same diets will end up different heights based on their genes. I used to think that intelligence was earned due to exercise and that others just needed to try harder. I’ve since seen enough people try really hard and fail that I no longer believe that. As with strength, some mutations give some people a big advantage. I don’t think it’s an assumption, there is a lot of evidence. Even the low studies have IQ at 50% DNA and that’s without the greater understandings we have today, I would put it at 80%. Plus likelihood of IQ supporting genes would be much much higher at the extremes.

[Kim_Bruning]

On the one hand, it is certainly very suggestive when you see that children's phenotypes very closely match those of their parents (though you do have to keep an eye out for confounders such as culture or environment even then).

On the other hand, if you try to actually predict things like height or IQ directly from some random genetic sequence someone puts in front of you ... well ... that turns out to be rather tricky.

Have you read any papers that give it a try?