If homosexuality is genetic then how come they havent breeded themselves out of existence?
What a great question. Maybe the Darwinists can provide the elusive answer.
An excellent question, and one for which there are many hypotheses and few accepted answers. Even if homosexuality isn't per se genetic, one might expect humans to have evolved resistance to homosexuality because of its high costs.
One argument I've seen is that a limited number of homosexuals might have increased fitness in an early society, if they were more likely to care for their younger siblings and for the children of close relatives.
From a selective point of view, an individual gets the same fitness from having a sibling survive to reproductive adulthood as they do from having children themselves, so evolution wouldn't have disfavored them.
There are many instances in nature where non-reproducing individuals confer advantages on their society -- see worker bees as one obvious example.