system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do men bald on their scalps but not their beards?
gpt
Testosterone. Scalp hair and facial hair are rather different. Testosterone sometimes converts into a chemical called DHT that breaks down scalp hair, but leaves facial hair alone. (It has to do with a specific gene) In fact, facial hair grows because testosterone is in the body, which is why it grows so much during puberty.