> Even if 60 percent of the increase is not real, there still is a very large real effect that remains unexplained. A major plausible proposed cause that didn'

> Even if 60 percent of the increase is not real, there still is a very large real effect that remains unexplained. A major plausible proposed cause that didn't get a mention is assortative mating (the effect may not be strong enough to account for all the remaining increase, though): https://pubmed.ncbi.nlm.nih.gov/31200929/ https://pubmed.ncbi.nlm.nih.gov/31200929/