Once again for the Cult Of The Gay Gene:
Pay attention, Del-Liar-O, to the beginning and the bulletpoints that tells you that you're wrong, and I have been right. Idiot.
http://www.religioustolerance.org/hom_caus10.htm
For decades, the root cause of homosexual and bisexual orientation has remained a mystery. Although many recent studies have given*strong indications*that the cause has a hereditary component, there remain some gaps in the scientific understanding of these two sexual orientations:
*No smoking gun* has been found so far. In spite of massive research efforts, no gene or group of genes has been definitively proven to cause homosexuality.
The Darwinian theory of natural selection is based on the survival of the "fittest" where fittest is defined as those members of a species that have the largest number of offspring. They are the individuals that most successfully pass their genes on to the next generation. Gays and lesbians, by definition, are not sexually attracted to members of the opposite sex and thus tend to have many fewer offspring. Bisexuals are attracted to the opposite sex to some degree, but are also attracted to the same sex. Thus both homosexuals and bisexuals tend to procreate less. If homosexuality is a trait with a purely genetic cause, one would expect that it would become very rare within a given population group in a few generations. Heterosexuals simply outbreed homosexuals and bisexuals. But every society on earth has a more or less a stable percentage of gays and lesbians. It would appear that a simple "gay gene" or set of "gay genes" may never be found because they may not exist.
Researchers at the Working Group on Intragenomic Conflict at the National Institute for Mathematical and Biological Synthesis (NIMBioS) have issued a report on epigenetics. They have produced a mathematical model that shows how epi-marks before birth might play a major role in determining a person's sexual orientation and perhaps even gender identity.
NIMBioS researcher Sergey Gavrilets explained:
"It’s not genetics. It’s not DNA. It’s not pieces of DNA. It’s epigenetics. The hypothesis we put forward is based on epigenetic marks." 1
According to a NIMBios article:
"Epi-marks constitute an extra layer of information attached to our genes' backbones that regulates ...[the genes'] expression. While genes hold the instructions, epi-marks direct how those instructions are carried out -- when, where and how much a gene is expressed during development." 2
These epi-marks are normally specific to the gender of the fetus. They are produced early in gestation, during the embryonic stage of development. The speculation is that some epi-marks "... affect the genitals, others sexual identity, and yet others ..." 2 affect the gender(s) to which the individual is sexually attracted later in life -- their sexual orientation. If this is true, then epi-marks may play a role in intersexuality, gender identity and sexual orientation.
Certain epi-marks become active later in pregnancy when they control the reaction of the fetus to normal fluctuations in testosterone levels. In the case of a female fetus, (XX) the epi-marks prevent her from becoming masculinized during intervals of high testosterone. For male fetuses, (XY) they prevent him from becoming feminized during intervals of low testosterone.
Normally, these epi-marks are eventually inactivated or "erased" during conception. They are not typically present to be transmitted from generation to generation. However, rarely, it is possible for these particular epi-marks to be transmitted at conception:
from the father to a girl embryo, thus allowing her to be masculinized later in gestation, or
from the mother to a male embryo, thus feminizing him later in gestation.
In both cases, the normal effects of the epi-marks would be inverted.
There is NO SMOKING GUN, NO CONCRETE EVIDENCE AS OF YET, So stfu.
Edited to comply with Copyright rules