03-10-2013, 06:12 AM
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Epigenetics: How our experiences affect our offspring
Epigenetics: How our experiences affect our offspring - The Week
January 20, 2013
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From Mendel and Darwin in the 19th century to Watson and Crick in the 20th, scientists have shown that chromosomes passed from parent to child form a genetic blueprint for development. But in a quiet scientific revolution, researchers have in recent years come to realize that genes aren't a fixed, predetermined program simply passed from one generation to the next. Instead, genes can be turned on and off by experiences and environment. What we eat, how much stress we undergo, and what toxins we're exposed to can all alter the genetic legacy we pass on to our children and even grandchildren. In this new science of "epigenetics," researchers are exploring how nature and nurture combine to cause behavior, traits, and illnesses that genes alone can't explain, ranging from sexual orientation to autism to cancer. "We were all brought up to think the genome was it," said Rockefeller University molecular biologist C. David Allis. "It's really been a watershed in understanding that there is something beyond the genome."
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Pregnant women who were traumatized at the World Trade Center on 9/11 were far more likely than other women to give birth to infants who reacted with unusual levels of fear and stress when faced with loud noises, unfamiliar people, or new foods.
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To the consternation of strict Darwinists, they can be. Researchers used to think that when a sperm and egg combined, all their epigenetic tags were erased, leaving the resulting embryo with a clean slate. Now they know that about 1 percent of our epigenetic tags escape erasure and pass directly to our offspring — and potentially their offspring and beyond. Scientists have discovered, for instance, that a group of children conceived during the Netherlands' desperate wartime famine of 1944–45 tended themselves to have smaller-than-usual offspring. That suggests that what men and women eat and smoke, and what toxins and traumas they're exposed to, can affect their children and even grandchildren. University of Texas zoologist David Crews has done multigenerational studies with rats that led him to speculate that soaring obesity and autism rates could be due to our grandparents' exposure to "the chemical revolution of the 1940s," including the introduction of new plastics, fertilizers, detergents, and pesticides.
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Now this is interesting.
One of the first things that came to mind, and before anyone gets all excited, it's just a thought, is that in history homosexuality seems to wax and wane. We're all taught in school that this is because of religious bigotry and suppression naturally. (Religious authority potentially conflicts with State authority and the State runs most schools.)
So I Googled the topic. Shazam! Apparently this is a hot topic in genetic research that has not yet been suppressed out of political expediency.
http://www.the-scientist.com/?articl...omosexuality-/
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Researchers looking for a genetic signature of homosexuality have been barking up the wrong tree, according to a trio of researchers in the United States and Sweden. Instead, the scientists posit, epigenetic influences acting on androgen signaling in the brain may underlie sexual orientation. In a paper published last week (December 11) in The Quarterly Review of Biology, they propose a model describing how epigenetic markers that steer sexual development in males could promote homosexual orientation in females, and vice versa. The scientists offer their model to explain both the tendency of homosexuality to run in families, and the fact that so far no “homosexual gene” has been identified.
“It’s a very provocative, very interesting new twist that is plausible,” said Margaret McCarthy, a neuroscientist at the University of Maryland who studies how hormones influence brain development and was not involved in producing the model. But, she cautioned, so far the theory “is not supported by any data.”
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Epigenetics Is A Critical Factor In Homosexuality
Epigenetics may be a critical factor contributing to homosexuality, study suggests
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According to the study, published online today in The Quarterly Review of Biology, sex-specific epi-marks, which normally do not pass between generations and are thus "erased," can lead to homosexuality when they escape erasure and are transmitted from father to daughter or mother to son.
From an evolutionary standpoint, homosexuality is a trait that would not be expected to develop and persist in the face of Darwinian natural selection. Homosexuality is nevertheless common for men and women in most cultures. Previous studies have shown that homosexuality runs in families, leading most researchers to presume a genetic underpinning of sexual preference. However, no major gene for homosexuality has been found despite numerous studies searching for a genetic connection.
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