There's enough documented cases where we KNOW this is the case to think this is likely true for a very large proportion of them. Dick Francis is a major case in point; his wife wrote most of "his" books.
Oh, not all those steps belonged to the guy here, to be clear. I don't think he's a misogynist. I just IDed him as a guy pretty quickly. He was so polite about removing himself I don't want people to think I think he's misogynistic!