Intelligence is the main trait that defines a human. How can it possibly be a defect? And I fail to see how it stand in the way of reproduction..
There is a diference between an error occuring in the genetic code and you inheriting one. The most common conditions which you described are common because it was inherited. Errors occuring on mass enough to justify even 1% of the population with a single condition is simply impossible
I can tell you why becosue I don't know. Could be that one of the first humans had that defect and it it indeed became quite common. Maby it is partially passed on. Maby its a error purposly built in by nature. Some things are just FAR more likely to happen than others, and we rarely can say why. Biology is a very complicated matter after all...
But if they are pressured to have offspring then surely that is because of their natural desires even if they prefer the same sex! It still leaves the obvious conclusion, they reproduce.
Less ofthen that heterosexuals, since sex with the opposite sex isn't appealing to htem. But let's look at something else, shall we?
When choosing your life partner you look for someone who's phisycal and mental traits you like. Not even in nature do they breed unselectivly. Basicly you'd want your offspring to inherit as much from your partner as possible. By homosexuals that doesn't happen. You don't breed with your chosen life partner, you (maby) breed with someone else. It takes 3 to tango for homosexuals. Maby in the future 2 will be enough, but it would still require some outside intervention.
Let's face it - when it comes to mating and reproduction, a heterosexual is what you might call "a streamlined and efficient design", while a homosexual is not.
If you got a car that has the gas pedal and break pedal wires crossed would you stop for once second before calling it a defect? No, you wouldn't. You can still drive it, but that just wan't in the original blueprints. A fully working car is simply nbetter at what it's supposed to do.
This is basicly my whole point, a undenayable fact.
Some of the things that define a human male/female, both physicly and socially, simply work much more efficient and streamlined for heterosexuals. Thus, homosexuality is a defects or an error if you will.
Now if you excuse me, I got 2 seminars to write...
*curses databases*