I'm pre-everything and I've had to shave since I was twenty-two. It's just a light moustache and a handful of hairs on my chin and neck. I figure it's genetic. Dad and Bro are both pretty hairy, and Bro had to start shaving when he was eight. No lie. Dude had a 'stache while he was in primary. Maternal grandfather, semi-hairy. Paternal grandfather, semi-hairy. Uncles, they vary with the hairy. Me, I just put out a lot of natural T already. Had blood analysis done in 2011 and it said my testosterone was eleven points over the max mark for females of my age range. [Then again, my mum kinda has to shave right now...and she's sixty-three...]
So, yeah, you have to look at your entire family tree, you have to consider your testosterone levels, and you may even have to look at your diet. Certain multivitamins will encourage hair growth. I take a Geritol every day and my hair grows really fast, not just on my head, but also my face. [It also makes me feel good and helps keep my anxiety levels down.]