It's all from your good genes.
My hubby when I met him, had bushy sideburns, and a full beard,they're thick & BUSHY like that of 30+, if you know what I mean. He was 21. He was in Alaska for a year, showed me a photo of him while there, and he looked so old with all that facial hair, (think lumberjack) and it was taken when he turned 20, he said he started when he was 18.
My sons, didn't start growing sideburns & beard until in their early 30's.
Male model for Kraft ZESTY Italian, is very hairy, so is Selena Gomez, whose father has Mexican DNA. I know she's very hairy, the last photo taken, before she cut her hair and dyed them blonde, inside was a photo of her wearing a back dress with a peep-hole opening, and they didn't airbrush it. NOT EVERY GUYS or girls have hair on their facial or pubes by the time they're 16. Some earlier, some even later.
Have you seen People's SEXIEST GUY? Channing Tatum, he was in the movie Magic Mike. He was 32 years old then, and he can only grow goatee, if you look @ the front cover, he has not have much facial hair. He said so, during his interview. So there you go!