Psychiatric Association, the American Psychological Association and the National Association of Social Workers in 2006 stated: There is currently no scientific consensus about the specific factors that lead an individual to become heterosexual, homosexual or bisexual, including possible biological, psychological and social effects of the sexual orientation of the parents. However, the available evidence indicates that the vast majority of lesbians and gay adults were raised by heterosexual parents and the vast majority of children raised by gay and lesbian parents grow up to be heterosexual. - [93] The Royal College of Psychiatrists in 2007 stated: Despite almost a century of psychoanalytic and psychological speculation, there is no substantive evidence to support the suggestion that the nature of parenting or early experiences of childhood play any role in shaping the fundamental orientation of a heterosexual or homosexual person. It seems that sexual orientation is biological in nature, determined by a complex interaction of genetic factors and the early uterine environment. Sexual orientation is therefore not a choice. - [94] The American Academy of Pediatrics stated in Pediatrics in 2004: Sexual orientation probably is not determined by any one factor but by a combination of genetic, hormonal and environmental influences. In recent decades, theories based on biological factors have been favored by experts. Yet there remains controversy and uncertainty as to the genesis of the diversity of human sexual orientations, there is no scientific evidence that abnormal parents, sexual abuse or any other adverse life event influencing sexual orientation. Current knowledge suggests that sexual orientation is usually established during childhood. Okay, so some questions may arise, such as: - Why in my day there was not as many gays now? For cultural reasons, sexual freedom and expression has been achieved in several countries, including Brazil, this leads to greater acceptance of homosexuality as part of people's lives, and increasingly, early teens want to be accepted by what they really feel, then there is a pressure that homosexuality to be no longer a taboo, as this taboo is broken as more homosexuals assume.- I'm straight and I had homossexual sex once and hadn't enjoyed, I'm gay? Homosexual behavior is well understood in animals and in man, in what situations where there are no females present, many males have homosexual behaviors, is the case of prisons, for example, or when for some reason in nature, there are no females available for mating . Sexual behavior can indeed be an isolated case of sexuality. A person may have made a choice to try and not like it, because it never felt attracted. Humans can rationally choose to suppress their instinctual desires and make choices often against their innermost desires. - I know a guy who has been married for life, had children and became gay. What happened? Well, humans are too complex to put everything in a few lines. It may be that your friend has always been bisexual, and chose one over the other. OR may also be that he was always gay, but then chose to live with the opposite sex, repressing homosexual desires