I remember reading about a study that occured near the turn of the century if I remember correctly. It was meant to study gonorrhea, which of course, was already known to be an STD. The researchers discovered that when a young girl in a house had gonorrhea, the father or another adult male always had it, too,
By turn of the century, you mean 1800s - 1900s, right? Freud's work on "hysteria" that scared the crap out of him showed incest was far more common than he was willing to believe, or to publicly state, anyway. It would be easier to invoke some unexplained increased childhood (actually girlhood) susceptibility to gonorrhea than to face the ugly truth they found.
At the turn of the last century (1900s - 2000s) we find the lingering (and false) myths that only males abuse and that males are never abused.
I guess progress is slow, but still progress.