I have never seen anything to show that sexual orientation is a static unchangeable thing. Peoples interest do change, and you can gain or lose sexual fetishes through life. You my be a breast guy then switch to loving legs betters. A straight person can become bisexual, and while it might be uncommon people do go from straight to gay, or from gay to straight.

Normally changes in things like that are so gradual that they are not easily noticeable, but it can and does happen. A person that suddenly notices they are gay, may really have at one point enjoyed and preferred the opposite sex.

Since it can change, it make it seems even less likely that things are set at stone at birth.

Also, you can be homosexual without actually loving a person. If you have great gay sex, but have no other feelings for them, you are still gay. Just like a straight person doesn't have to love their partner, neither does a gay person. Now I am not saying most people are like that or anything, but it does count.

Any way, to get back on the abnormality topic. My entire point was that being gay is a personality trait and a preference, and no preference is ever abnormal because humans are individuals and we are all different and capable of doing whatever we want.