"In a few cases (N < 5) families were dropped from the comparison group because some history of sexual abuse was ascertained."
So roughly 5% (<5 of 84) of the control group were discovered to have themselves been abused and needed to be dropped from the study. I was once in a law lecture on medical ethics. We were discussing genetic testing of newborns and how this could detect incest/abuse. A medical doctor in the class was dead against such testing. In his experience, amongst pregnant teenagers (17 and younger) about 10% were pregnant by their own fathers/brothers. His opinion was that our society is not ready to deal with this, that such abuse is far more common than anyone is willing to admit. He actually said: You better build some more prisons before you start testing babies for this. The OP study seems in line with his numbers.
"In a few cases (N < 5) families were dropped from the comparison group because some history of sexual abuse was ascertained."
So roughly 5% (<5 of 84) of the control group were discovered to have themselves been abused and needed to be dropped from the study. I was once in a law lecture on medical ethics. We were discussing genetic testing of newborns and how this could detect incest/abuse. A medical doctor in the class was dead against such testing. In his experience, amongst pregnant teenagers (17 and younger) about 10% were pregnant by their own fathers/brothers. His opinion was that our society is not ready to deal with this, that such abuse is far more common than anyone is willing to admit. He actually said: You better build some more prisons before you start testing babies for this. The OP study seems in line with his numbers.