Genetics for the androgen (male hormone) receptor is involved in the process of balding, because balding is dependent on testosterone. Dozens of other genes involved too.
But he was surprised when he became bald.
Francis never expected to become bald, because his Dad was never bald. He decided to do some research.
Francis reads an article explaining that balding can be caused by a gene in the X chromosome, which would mean his Mom gave him his baldness. But the article said this is not always true because there are many other genes that affect hair loss.
Francis looked at his family tree to see who was bald, that way, get the phenotypes of his family. Francis noticed there was no baldness on his father's side, and he knew his Dad couldn't have it because baldness is generally sex-linked, so he couldn't be a carrier. Francis noticed the prevalence of baldness on his Mother's side. She definitley could have been a carrier.
What do ya know? Francis got his baldness from his mother.