JonnyD said:
Maybe not you, but a lot of us
were born shy. I was extremely shy (worse than now) from the earliest point I can remember, and nothing happened to make me that way. My earliest memory is the horror of approaching pre-school on the first day knowing that I'd be stuck with strange kids... and I know even before that my parents say I was scared of strangers. Talking to people, the rare times I've done it, has never led to any negative consequences that I recall. There's nothing learned about it.
It's more complex than one gene, it's more complex than being hypersensitive, but there's certainly a genetic predisposition towards social anxiety which some of us have.
Perhaps progress can still be made to overcome a genetic predisposition, though.