Heritability (i.e. narrow-sense heritability as typically used in most research articles) is not so clear-cut as to be split between nature and nurture. Even the GP is slightly incorrect when saying:

> ...as opposed to environmental factors

because for heritability, the distinction is between the variance explained by additive genetic effects versus the total variance of the trait of interest. There are other sources of phenotypic variance like epigenetics, non-additive genetic effects, or complex interactions that fall outside the scope of heritability.

We have 3 sources of difference, genetic heritability, home environment and "others". The things you talk about would go under "others", and they aren't very interesting since we have basically no influence over them, as everything we can influence via nurture goes under home environment and nature via genetic heritage. So for example, of we compare growing up in a rich or a poor household (this includes going to a better school, better neighborhood, better food etc), most of these studies shows that it has almost no effect at all.

You influence "others" by putting your kids in a good school.

It's one of the main drivers of varying housing costs in the US.

School is included in the shared environment because if you had identical twins they would be going to the same school and same classes.

Your parents determines your school, so the quality of your school can't be in "others". The only way school could be in "others" in these studies is if parents often put one twin in a good school and the other twin in a bad school, but I strongly believe that isn't the case.

Your parents don't in all cases. I went to a good school and my brother went to a bad school. My parents didn't choose that. The good school did, it was selective in its students. Selective school aren't all that rare.

In your own words:

> We have 3 sources of difference, genetic heritability, home environment and "others"

Clearly, school is not home environment.

School is determines by your home environment, hence it is a part of the home environment bucket. "other" is not: "everything except home environment and genes", it is: "everything not determined by the home environment or genes".

I don't think this negates the parent's concern.

The parent uses an extreme example, but I think the underlying concern is: what assumptions get baked in when we assume the available environments are pretty normal?

Our modern environments are very abnormal compared to human environments for most of human genetic history. We can measure traits of statistically "normal" humans living in statistically "normal" environments and still ultimately be sampling in a weird corner of the possibility space.

Normal as in there is very little difference between the lives of most people in first world nations. They go to a school for a decade and don't have to worry about sleeping out in the rain or going hungry. That is enough for kids to bloom. If you deny them any of those then there are problems, but that is not an issue even for poor people in the west.

>They go to a school for a decade and don't have to worry about sleeping out in the rain or going hungry. [...] but that is not an issue even for poor people in the west.

Ooof. Just FYI this is actually horribly out of touch with reality. Go talk to a social worker sometime, or someone that runs a soup kitchen/shelter.

Or just check out the official government stats for the US: https://www.ers.usda.gov/topics/food-nutrition-assistance/fo...

To quote: "Both children and adults were food insecure in 7.1 percent of households with children (2.7 million households.

Although children are usually protected from substantial reductions in food intake even in households with very low food security, nevertheless, in about 0.6 percent of households with children (220,000 households), one or more child also experienced reduced food intake and disrupted eating patterns at some time during the year."

> we can still look at the overall population distribution and say something relevant about heritability since most people have pretty normal genes and environments

So if you had some groups with generally fairly different genes and environments both, this would ascribe any differences just to the genes and throw out the environment aspect?