Rereading and trying to guess at what you mean – if your point is that older research said corporal punishment was harmful to both sexes, I agree that that is what a lot of researchers claimed during the 1970s and early 1980s, and I am sure they believed their claims were accurate. However, there was a huge problem with their studies and that is that they assumed gender differences didn’t matter, and so they didn’t look at them at all. They just grouped all children together.
If 90% of girls and 20% of boys report something, then assuming equal numbers, if you just gather the data without looking at gender, you get “55% of children reported…”