The question arises as to what kinds of epigenetic changes could affect individuals systematically but also affect gametes whereby transgenerational inheritance would be feasible. Adrenodoxin is an iron-sulfur protein that is essential for the synthesis of various steroid hormones. A difficulty in synthesizing iron-sulfur proteins could result in low levels of adrenodoxin. Adrenodoxin is a co-factor for cytochrome P450 enzymes where some P450 enzymes affect the synthesis of estrogen. Decreases in adrenodoxin levels would decrease activity of P450 enzymes which could increase methylation of P450 genes. With genes not being transcribed due to decreased activity of enzymes transcription factors are not blocking genes from becoming hypermethylated. Decreased activity of enzymes could increase methylation of genes of such enzymes on a use it or loose it principle. As adrenodoxin is demanded for the synthesis of steroid hormones dysregulation of adrenodoxin could give rise to various phenotypes where epigenetic changes in parents are inherited by children due to concomitant alteration of gametes. Adrenodoxin is highly expressed in male and female tissues. Various enzymes that demethylate DNA in embryos would also have to be dysregulated. The devil is always in the details and the details are not worked out. Dysregulation of adrenodoxin only in the fetus could result in dysregulation in testosterone or estrogen in the fetus which could lead to epigenetic changes whereby gays are born gay.
If there is not transgenerational epigenetic inheritances in humans evolution missed a very effective way to maintain cultural advances while at the same time also not locking in the biological basis for such cultural advances leaving room for further cultural advances. Transgenerational epigenetic inheritances fit all of human history. ‘Cultural osmosis’, the leading theory of cultural transmission is a very foggy notion of how cultural transmission works and will always be a very foggy notion of how cultural transmission works.