We asked a dermatologist to explain the scientific reasons that some men aren't able to grow thick, dense facial hair. Dr. Jennifer Chwalek is a Board Certified dermatologist at Union Square Laser Dermatology in New York. Chwalek explained that an inability to grow thick facial hair is not directly related to low levels of testosterone. Facial hair growth is largely determined by genetics, which can determine the number of hair follicles a person has, as well as how the follicles react to a byproduct of testosterone known as dihydrotestosterone.

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Following is a transcript of the video:

Narrator: Look at that beard. The density. The thickness. It's what a beard is supposed to be! Not this. This is my beard, if you even want to call it a beard. This footage was taken after I let it grow for two weeks. Two weeks! It's thin, patchy, and in some spots there's no hair at all. Sad. But let's look at this one again. This is Kevin. We're around the same age, both Caucasian males of Irish descent. You could say we have a lot in common, except in the facial hair department. So, I asked a dermatologist about why he's able to grow a beard and I'm not.

Dr. Jennifer Chwalek: It's based on genetics as well as hormones. Some men, you know, have more hair follicles, so they can grow denser, coarser beards than others. Testosterone gets converted in the hair follicle to a more potent form called dihydrotestosterone. Some hair follicles have receptors on them that are very sensitive to this higher form of testosterone, dihydrotestosterone, and that will stimulate hair growth.

Graham Flanagan: How would you characterize my facial hair?

Dr. Chwalek: I'd say it's like, sparse, and you have light-colored hair, so it doesn't show up quite as much.

Flanagan: I can't really grow a great beard. It's been a problem. I want one. I wanna look like my colleague, Kevin. I mean, look at that beard. It is just glorious. Why can't I grow a beard like Kevin?

Dr. Chwalek: Well, Kevin has some good hair genes, so because of that, the hair follicles on his face are more sensitive to the effects of a form of testosterone called dihydrotestosterone which can help to stimulate thicker, coarser, longer hair growth in some areas of the body like the beard area.

Narrator: Beards and facial hair have long been associated with masculinity and virility. I began to wonder if my inability to grow thick facial hair like Kevin makes me less of a man.

Flanagan: Does the fact that I can't grow a beard, does it make mean that I have low testosterone?

Dr. Chwalek: No. Men who can't grow a beard or have patchy beards usually have normal testosterone levels. It isn't a reflection of having low testosterone or being deficient in testosterone.

Flanagan: So, you can still be virile —

Dr. Chwalek: Right.

Flanagan: And grow a crappy beard like this?

Dr. Chwalek: Yes.

Flanagan: Okay, good.

Narrator: And in fact, there are some ways to increase the chances of growing facial hair, but shaving more often isn't one of them.

Dr. Chwalek: So, the idea that shaving can impact hair growth is actually a myth. When you're shaving, you're just cutting the hair off at the surface of the skin, and what's controlling the hair growth is really occurring deeper in the skin. So, it shouldn't have any impact on how quickly the hair grows, or how dense the hair grows. People have tried topical Rogaine or Minoxidil. These things may stimulate a little hair growth, but assuming it's due to genetics, then you're kind of stuck with what you have.

Flanagan: It's all about the sensitivity of the hair follicles and how they interact with this —

Dr. Chwalek: Dihydrotestosterone or androgens in the blood.

Flanagan: So, you're saying that, that his hair follicles are "sensitive."

Dr. Chwalek: Yes.

Flanagan: See, mine aren't.

Dr. Chwalek: Right.

Flanagan: They aren't sensitive. They're like rocks. They have no sensitivity at all. Okay, so I win that!

Dr. Chwalek: Right.

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Why Some Men Can't Grow Beards