As a mother, it seems I feel compelled to try to defend the moms who are mentioned here as less than 100% supportive. So many factors play into a mom's response. I shouldn't play amateur psychologist but---maybe lack of response is caused by overwhelming guilt that makes it easier to deny it ever happened. After all, a parent's job is first and foremost to protect a child. Knowing that we've failed in that regard is truly awful. Then, too, there may be the emotional need to remove oneself from the situation in order to live past it.
i know why she closed her eyes and refused to see it. she and her mom and sister were abandoned by her father when she was very young. they had a very difficult time surviving. my father died when i was 3 and she was needing security and material support for herself, my brother and me. history was repeating itself. i'm sure in her mind it was too scary to contemplate losing the comfortable life she had just re-gained and going back to wondering how she would support her kids. and then - things like that didn't happen in nice families - and we were definitely nice. it was easier to believe that nothing was wrong and that this was how dads disciplined the naughty boys under their care.
i benefited materially from that decision just as she did - nice house, clothes, good food, cars, vacations... but i feel like i was the one who really paid the price for the life-style we enjoyed.
thanks for the other kind comments. i wasn't meaning to fish for compliments or sympathy. and i don't blame you. your situation was different, i'm sure.
i was very good at hiding what was happening once i realized that it upset her. i tried to protect her from the knowledge. it was a 3-way conspiracy: the abuser, the abused/protector, and the protected/intentionally blind.