text: what is the origin of homo sexuality? actually i want to know wheather the born(fetus) disorderis the main cause of homo sexuality? studies have found that the hormones a foetus is subjected to before birth may well play a part in determining the person's sexuality in later life. the hypothalamus, a small lobe that hangs down at the base of the brain and is linked to sexual intercourse, has been found to play a significant role. in a study it was proved that the size of the hypothalamus in homosexual men is more alike to the size of a heterosexual females, not a heterosexual male. as the hypothalamus develops before birth it can be argued that homosexuals were 'born that way'.  also there is statistical evidence to state that homosexuality can be hereditary. it can be passed through the female line (for example, gay man (who has a sister) has a gay nephew through her, and then this gay nephew would in turn have another gay nephew through his sister and so on down the family tree). this means that a homosexual gene is probably passed on through the x chromosome. with all this evidence it seems doubtful that the origins of homosexuality are anything other than biological, and people who believe otherwise like that guy at that top... urban something are just showing their ignorance. hope that answers your question!