There is no genetic evidence of homosexuality as of yet, hence it is probably not something that can be inherited.
As for it being something the human brain is likely to implement due to its psyche or make-up e.g. heterosexuality, virtues of curiosity, communication, etc--that is debatable. I personally believe that if homosexuality was something we were 'bound' to, then our organs would be adjusted accordingly. There are worms with both functional male and female organs, penguins can have birth even with the same sex--then why not us as human beings? Eve if we defy the existence of a High Authority behind this, but we see in Science that every chemical reaction, chemical reactant, physical design, chemical environment--whatnot--has a definite reason and purpose.
Also, most homosexuals in modern times, even, usually have had extensive heterosexual relationships before involving themselves in homosexuality. Homosexuals are also known to revert to heterosexuality.
I know these facts can be interpreted openly, but to me it makes enough sense from lack of genetic evidence (with the Human Genome Project going on, we can hope to find out soon) and the physical design of human beings, that it's a simple fallacy of sorts, giving ourselves an 'open' option to expand our 'thoughts'. I don't mean to offend any homosexuals or supporters of homosexuality on here, but this is my point of view.