increased testosterone from working out is probably around 10-30% long time, which is a far lower variance than natural level variance in healthy adults. i think i heard from several (claimed natural) strength and bodybuilding athletes that their total testosterone is at the lower end of the scale.
that said, natural free test levels are at a fraction of what enhanced pro bodybuilders tend to supplement, and there are mass monsters with hair. cutler, yates, ferrigno and golden era bodybuilders like schwarzenegger, zane, columbu all had full heads of hair.
Yeah, wanted to point this out. I have mid-range natural test levels, more than my dad, and don't have any signs of balding. My dad lost half of his hair by the time i was born.
Steroid consumers have al least ten times my leves, and while this is a factor indeed, in is not necessarily decisive.