A genetic predisposition for homosexuality may also come along for the ride with genes that have other effects. It has been mentioned before that some studies were done that showed a correlation between homosexual men and increased fundicity in their sisters. Theoretically then, it is possible for a homosexual man to have no offspring yet the 'gay gene' would be perpetuated by his sister.
Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)