It's highly genetic but, I was the least hairy person you could find, I didn't start shaving until 23 I think, clean chest/back/shoulders/etc.
Anabolics made me seem to start shaving more often, but also grow hair on back and shoulders. This is only when using. I literally have like 8 on my back but they get long as hell if I don't take care of them but my shoulders are starting to get worse.
I started shaving shoulders and chest, it seems to make it worse even though everything I read says there is no truth to that.
So I have my girl pluck the few on my back, and shoulders I'll shave or use a cream. Either way sucks. I hate body hair, but I'm not paying for it to be removed.
So yea it can definitely grow hairs in odd places and probably makes it worse if you already are genetically hairy.