Plus pour revenir d'un autre point, voilà une expérience qui a fait parler.
http://www.hollanddavis.com/?p=3647
"Eight major studies of identical twins in Australia, the U.S., and Scandinavia during the last two decades all arrive at the same conclusion: gays were not born that way."
"Identical twins have the same genes or DNA. They are nurtured in equal prenatal conditions. If homosexuality is caused by genetics or prenatal conditions and one twin is gay, the co-twin should also be gay.
Because they have identical DNA, it ought to be 100%,” Dr. Whitehead notes. But the studies reveal something else. “If an identical twin has same-sex attraction the chances the co-twin has it are only about 11% for men and 14% for women.”
Because identical twins are always genetically identical, homosexuality cannot be genetically dictated. “No-one is born gay,” he notes. “The predominant things that create homosexuality in one identical twin and not in the other have to be post-birth factors.”
Dr. Whitehead believes same-sex attraction (SSA) is caused by “non-shared factors,” things happening to one twin but not the other, or a personal response to an event by one of the twins and not the other.
For example, one twin might have exposure to pornography or sexual abuse, but not the other. One twin may interpret and respond to their family or classroom environment differently than the other. “These individual and idiosyncratic responses to random events and to common environmental factors predominate,” he says.
Even more remarkable, most of the changes occur without counseling or therapy. “These changes are not therapeutically induced, but happen ‘naturally’ in life, some very quickly,” Dr. Whitehead observes. “Most changes in sexual orientation are towards exclusive heterosexuality.”
Numbers of people who have changed towards exclusive heterosexuality are greater than current numbers of bisexuals and homosexuals combined. In other words, ex-gays outnumber actual gays.
The fluidity is even more pronounced among adolescents, as Bearman and Brueckner’s study demonstrated. “They found that from 16 to 17-years-old, if a person had a romantic attraction to the same sex, almost all had switched one year later.”

Selon cette étude, il est clair que personne n'est né gay (génétiquement) et que ce sont les influences externes ou après la naissance qui rentre en compte.
Plus, voilà POK concernant le role du porno sur la possible attirance sur le meme sexe.
https://www.yourbrainonpo[...]racted-to-gay-transsexual ([Porn Induced] homosexual obsessive compulsive disorder , montre l'influence externe sur la perception sexuelle et donc la très forte possibilité d'autres élements externes qui rentre en compte en faveur des relations gays)