When I was a child we had a set of books, like an encyclopedia, of sort of common sense life information. In the personal hygiene section it recommended brushing your hair daily and washing it once a month. The books were published around 1930, IIRC. I wish I still had them. They would be fascinating to read today.
BTW, My Dad was bald at 35 which he variously attributed to being forced to wear a helmet during WWII, friction on the bedstead headboard or wind in his hair from riding horses. Meanwhile, I, at 70, still have a full, if thinning, head of hair. This even though I wore a steel pot for more years than Dad did and rode motorcycles without a helmet. Must have been the other thing.
baldness skips generations