In the Fritzl incest case in Austria, how did the wife not know......?

Question

I believe the wife did not know, but how did she not know, it said they raised 3 of the incest kids as their own, where did the wife think the 3 kids had come from?

Answer 1

Fritzl forced his daughter write notes that she was in a cult, and she couldn't raise her babies.  He would then bring the babies into the house claiming that his daughter had left them on the front porch with the notes.

Answer 2

I wonder the same thing.  Why would she not go down to her basement for 15+ years?  Seems VERY strange to me and I tend to think that she did know.