Posted on 04/01/2013 12:23:05 PM PDT by abigailsmybaby
ABSTRACT Male and female homosexuality have substantial prevalence in humans. Pedigree and twin studies indicate that homosexuality has substantial heritability in both sexes, yet concordance between identical twins is low and molecular studies have failed to find associated DNA markers. This paradoxical pattern calls for an explanation. We use published data on fetal androgen signaling and gene regulation via nongenetic changes in DNA packaging (epigenetics) to develop a new model for homosexuality. reduced androgen sensitivity in XX fetuses and enhanced sensitivity in XY fetuses, and that this difference is most feasibly caused by numerous sex-specific epigenetic modifications (“epi-marks”) originating in embryonic stem cells. These epi-marks buffer XX fetuses from masculinization due to excess fetal androgen exposure and similarly buffer XY fetuses from androgen underexposure. Extant data indicates that individual epi-marks influence some but not other sexually dimorphic traits, vary in strength across individuals, and are produced during ontogeny and erased between generations. Those that escape erasure will steer development of the sexual phenotypes they influence in a gonad-discordant direction in opposite sex offspring, mosaically feminizing XY offspring and masculinizing XX offspring. Such sex-specific epi-marks are sexually antagonistic (SA-epi-marks) because they canalize sexual development in the parent that produced them, but contribute to gonad-trait discordances in opposite-sex offspring when unerased. In this model, homosexuality occurs when stronger-than-average SA-epi-marks (influencing sexual preference) from an opposite-sex parent escape erasure and are then paired with a weaker-than-average de novo sex-specific epi-marks produced in opposite-sex offspring. Our model predicts that homosexuality is part of a wider phenomenon in which recently evolved androgen-influenced traits commonly display gonad-trait discordances at substantial frequency, and that the molecular feature underlying most homosexuality is not DNA polymorphism(s), but epi-marks that evolved to canalize sexual dimorphic development that sometimes carryover across generations and contribute to gonad-trait discordances in opposite-sex descendants.
(Excerpt) Read more at jstor.org ...
How about protecting sexually impressionable kids by any means necessary from adult homosexuals who prey on them for sex and diddle them? That would also include keeping them out from under the influence of those who don't have sex with them but indoctrinate them endlessly on the acceptability of homosexuality in our "public education" cesspools.
Would that help prevent the "canalization" of those mysterious "stronger-than-average SA-epi-marks"?
I'd bet it would. Big Time...
Thank you for the reply. You at least confirmed that this is largely beyond my basic biology education.
By “expressed” I did mean this in terms of the appearance or behavior of the organism. By “better” I meant of survival benefit.
It seems counter-intuitive to me that the appearance or behavior most likely to appear in offspring would be detrimental to its survival, at least if the concept of natural selection is to be believed. I take your word for Huntington’s, but I expect that this dominant/recessive gene phenomena is overall selecting for survival in most instances.
Brown eyes (and skin pigment) may be “better” for survival. Too much Sun may be far worse than too little. Our view of what is “better” may be subjective, but I expect that survival in the natural world is cold and pragmatic.
By “cast in stone” I meant that I thought (guessed) that the gene seen dominantly expressed, say in current man, may not always be so. Your example of the digger/filler is what I was thinking of. Both genes are there and are trying to signal the action they are coded for, but something else in the overall organism makes one more effective than the other. I expect that this can change.
That’s why I posted this. That’s what I understood it to suggest and I was hoping someone with a scientific background would tell me if I was off base. At one point they state that (I’m paraphrasing) the baby could be protected at some point during gestation from this phenomenon taking place .
Learn the English language. -ity denotes a state or condition or essence, not an act.
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