Inertia Posted:

Or is it a developmental error produced later in life?

This is a very important and relevant question.

Interesting question, although you won’t find the answer here. The debate has been going for quite a while, and I don’t believe it’s been fully resolved. I would bet that there’s a strong genetic basis to it, but it’s also influenced by culture, upbringing, demographics, etc.

Here’s a good start if you’re interested in reading about the arguments:

http://en.wikipedia.org/wiki/Biology_and_sexual_orientation

http://allpsych.com/journal/homosexuality.html

http://www.boston.com/news/globe/magazine/articles/2005/08/14/what_makes_people_gay/

tl;dr They’ve been looking for the “gay gene” for some time now and haven’t quite found it, but they found several biological fingerprints that predict homosexual behavior, such as finger length and scalp-hair whorl rotation.

I’d also say it’s pretty offensive to call it a “developmental error.” There are many compelling evolutionary theories as to why homosexuality exists (in humans and in all species). Besides, not all sexual behavior has to contribute to procreation. If it did, blowjobs would cease to exist, and that’s not the kind of world I want to live in.

Here’s an interesting discussion, but there’s plenty more on the webs: http://evolution-101.blogspot.com/2006/07/why-did-homosexuality-evolve.html