Is homosexuality a genetic disorder?

No. Homosexuality may have a partially genetic basis, but it is not a disorder and not chromosomal.
NO! Homosexuality is not considered a disorder. A specific genetic predisposition toward heterosexuality has not yet been found.
No. Best evidence is that sexuality of most gay males is determined while they are still in the uterus. The likelihood of a woman's son being gay increases with each subsequent male child but only right handed males. The first son and all left handed males have a 2% chance of being gay. The third son if right handed is actually more likely to be gay than straight.