Why do some men have patchy beards? Or more specifically, why would some hair follicles lack sufficient 5-alpha reductase while others nearby don't when their genetic code is identical and they are both the same type of cell? (See below.)
(Though my actual question is more broad in nature, the answer to this particular example should give me what I'm looking for.) On this website (http://beardcoach.com/2009/11/why-you-have-a-patchy-beard/) explaining why some men grow patchy beards it says:
"When the dermal papillae of your beard follicles utilize testosterone, they actually metabolize it and create another androgen as a byproduct called dihydrotestosterone...To utilize testosterone and create dihydrotestosterone, your beard follicles need yet another substance, an enzyme called 5-alpha-reductase. This enzyme is necessary for this conversion, and if you have low levels of it, then you have low levels of dihydrotestosterone. More importantly to the topic at hand, if you don’t have enough 5-alpha-reductase, the dermal papillae of your beard follicles can’t properly use testosterone to tell your hair matrices to make hair. And if your beard hair matrices aren’t making hair, you aren’t growing a beard."
What it doesn't explain is why certain hair follicles have sufficient hormone (or enzyme to utilize it) and others don't.