Just look to your mother’s father! - Why this advice is not useful
Okay, dudes on testosterone, I know we’re all a bit afraid of losing our majestic locks of hair we’ve cultivated for so long as we age as transmen. I understand your fear! My mom’s hair is thinning, my dad is going bald, neither of my grandfathers have hair, what’s a boi to do?
When predicting if you’ll have male-pattern baldness, all of the advice given is, “Well just look to your mother’s father!”. Here’s an explanation why this tidbit of advice is good for cismales. Genetic research has shown that male-pattern baldness is largely an x-linked recessive trait, however there are non-sex-linked genes involved as well. Cisguys, as you all should know, have XY sex chromosomes (most of the time). They got their X from their mom, and their Y from their dad.
Now here we focus on the maternal genetics, since she’s the one giving the X and the trait is on this chromosome. So the mother is XX, she got one X from her father and one from her mother. If her father is bald, he could be carrying the recessive X, which he passed on to her. Since the cismale’s mother has two X’s to give, the cismale, if his maternal grandfather is bald, has a 50% chance of receiving that recessive X and WALLAH!
However, for transmen, we have two X’s. For male-pattern baldness to occur to us, our fathers must be bald/going bald and our mothers must at least be carriers - their father’s must be bald/going bald or their mothers be carriers. You can see how this is getting kind of messy. You will FOR SURE go bald if your mother has male-pattern baldness as well as your dad. Beyond that, it’s really difficult to tell.
Female pattern baldness is an entirely different ballgame and is affected by the actions of androgen hormones. Female-pattern baldness is diffuse and goes around the entire top of the head and can affect XX individuals at any time.