A comment below from John:
Love to see a post about which human traits worth caring about are notable for having little or no hereditary component. It is all good and well to know what we cannot change, but it makes more sense to focus personally and as a parent on those things that aren’t genetically preordained.
This is a common sentiment I’ve seen. If you haven’t read The Nurture Assumption, please do so. I’d say a substantial reason I think that The Blank Slate is a good book is that Steven Pinker promoted Judith Rich Harris’ work.
With that out of the way: the implication in the comment above is that hereditary traits are the ones you have least control over, so you should focus on the non-hereditary traits. To some extent there is truth in this. Micronutrients are important. You don’t want to turn you children into cretins.
But a major problem with the idea that we can impact environmental impacts on characteristics is that on many traits we don’t know what those environmental impacts are. You can take a behavior genetic model and come to the following conclusion: within the population 50% of the variation is due to genes, 40% of the variation is due to non-shared environment, and 10% of the variation is due to shared environment (parents). We don’t really usually know what the non-shared environment means. It might be just developmental noise. It might be epistatic genetic effects. Or, in relation to behavior, it might be peer group, as Judith Rich Harris asserts.
We just don’t know. What that means is that the hereditary components are what you have legitimate effective control over through mate choice. And shared environment. These two combined are not nothing. And of course there is the impact of nation or community on the environmental in which propensities are expressed.
Addendum: The non-shared environmental variance was once explained to me as a “noise” factor. Just to give you a sense of how well we understand it.