The few times I tried to grow out a beard at a younger age, It was pretty uniform and full, but when I was perhaps 24 I was playing dodgeball in a gym, and was the last one in.
I had just thrown myself to the ground to avoid a ball, rolled onto my stomach and looked up, only to see a ball sailing right at my upturned face.
I involuntarily ducked, slamming my chin into the floor, bashing it pretty well. It took a while to heal (no stiches) but when my beard began to grow in after that, it had these spots of white hair I didn’t like, so I didn’t grow one often after that except for an occasional short lived goatee.
For the last four years or so, when I shave, my entire head is covered with shaving cream except for eyes, mouth, and ears, and it all gets shaved off!