Sexuality is a learned process, sometimes from very early on, and taken from experience (directly or indirectly) from a whole host of sources, from playground banter to seeing porn to (unfortunately for some people) physically experiencing at a young age, and all points inbetween. From there, we learn and (in most cases) understand our sexual orientation. Whether society any given person lives in allows us the freedom to express that sexuality depends on the context.
Wow. So kids are more likely to end up homosexual if they grow up in Brighton and exposed to all the gayness?!