A lot of people told me I went bald on top because I wore a ball cap practically 24/7 for so long. If that's true, I regret wearing it so much, but I'm pretty sure baldness is genetic.
My hair went through some weird phases while I had it. It was pretty straight when I was a kid, turned wavy when I went through puberty, got super curly after I took up salt-water scuba diving, and then went straight again when it started thinning...but only on the top. When I let what's left of it grow out, it's curly in the back and straight on the sides.
It's like my hair couldn't decide if it was Jewish or Irish, and it finally just gave up and fell out.