twentysixpoint2 saidQuestion: what causes chest hair, in my teens and 20s I've had none, but now I have about 10. They are growing in gradually. I have a twin and he has none still. I don't know what to make of its sudden appearance especially so late in life....
I'm no expert on WHAT causes it late in life, but I'm someone who's experienced the same thing.
I had no chest hair until my 30s, and then only randomly. Lots of leg & arm hair, and pubes like a forest, but nothing on the torso.
Going into my 40s the leg hair disappeared, the arm hair thinned a bit, but the chest has sprouted. Worse, from my standpoint, my back has become a nightmare, and some BFs have insisted that I shave it.
I had to start shaving my face daily at 12, and my thick beard has always been like sandpaper. Made a stunning mustache & beard, though, until turning white made me lose it. Not sure if there's any relationship between my face and my body hair history. And I suspect a lot has to do with genetics, not entirely about testosterone.