Does male-pattern baldness come from the mother’s side?
Feeling a little light up top? Or perhaps just concerned that it’s only a matter of time until you or a loved one does? Maybe you’ve heard that male-pattern baldness comes from the mother’s side and you’ve been viewing dear old gramps and his bald pate in a new and dreadful light. Perhaps you are dear old gramps and you’ve been scaring the young folks with tales of comb-overs to come. Well, it is true that the mother’s genes play a big role in male-pattern baldness, but the father’s genes play a part too.
The idea is that the faulty gene that leads to premature hair loss and subsequent identity crisis in human males is on the X chromosome. Now the X chromosome is special because it, in conjunction with the Y chromosome determines sex. If you have two Xs you’re a female, while if you have an X and a Y you’re a male (don’t take my word for it — whip out your microscope and check for yourself).
Now this scheme is very simple but it does have a flaw. Sex determination isn’t the only job of the X chromosome: it contains genes which are essential for all kinds of things. If a man has a particular form of one of those genes then he is at risk of developing early-onset male-pattern baldness. And because that X chromosome must come from his mother — his father has to contribute the Y chromosome or he wouldn’t be a he — that genetic factor can only reflect his mother’s side of the family.
I could say that this is a half truth, but I can be even more precise: it’s something like a 40% truth. That’s the proportion of risk that can be attributed to the X chromosome. But baldness, like most traits, is also controlled by genes on other chromosomes that can be inherited from the father or the mother.
So if you’ve been blaming a parent for that rapidly receding hairline, shame on you. They’re both to blame — let them shoulder it together.