> It's much, much more likely that a lot of those gene changes overlap, meaning combined changes won't affect the IQ any more than either/or changes would.
No, it's not. Please see Hsu's extended comments on the topic of interaction and non-additivity at the top of the page, and note the support from twin studies & GCTA. The point of his suggested strategy is that you're targeting the subset of gene changes in total heritability which don't do that.
No, it's not. Please see Hsu's extended comments on the topic of interaction and non-additivity at the top of the page, and note the support from twin studies & GCTA. The point of his suggested strategy is that you're targeting the subset of gene changes in total heritability which don't do that.