New Knowledge

That's interesting. From Genetic and environmental influences on adult human height across birth cohorts from 1886 to 1994 by Aline Jelenkovic, et al.

Human height variation is determined by genetic and environmental factors, but it remains unclear whether their influences differ across birth-year cohorts. We conducted an individual-based pooled analysis of 40 twin cohorts including 143,390 complete twin pairs born 1886–1994. Although genetic variance showed a generally increasing trend across the birth-year cohorts, heritability estimates (0.69-0.84 in men and 0.53-0.78 in women) did not present any clear pattern of secular changes. Comparing geographic-cultural regions (Europe, North America and Australia, and East Asia), total height variance was greatest in North America and Australia and lowest in East Asia, but no clear pattern in the heritability estimates across the birth-year cohorts emerged. Our findings do not support the hypothesis that heritability of height is lower in populations with low living standards than in affluent populations, nor that heritability of height will increase within a population as living standards improve.

If I knew this, I had forgotten. There is gendered heritability variance? I.e.

Although genetic variance showed a generally increasing trend across the birth-year cohorts, heritability estimates (0.69-0.84 in men and 0.53-0.78 in women) did not present any clear pattern of secular changes.

I am not even sure how to interpret that. If heritability of height in men is 0.69-0.84, does that mean heritability from father to son or son from both parents? I think the latter.

Taking the average of the ranges, I interpret this to mean that variance in a man's height is 77% determined by parental genes affecting height whereas a woman's height is only 66% determined by parental DNA. I would have thought that degree of heritability would have been the same. If that is not true, then why is there variance? Does that variance apply to all heritable traits and does the degree of variability differ by trait?

Hmmm.