It sounds wierd, but I think anytime a Mother is involved in incest it's more disturbing than a father. I would be really interested in any links to Narcissa/Draco, but really I'd like to see if anybody has written any Molly Weasley incest slash.

I think maybe the whole mother/father thing... it's a stereotype, but the father is less closely connected to the child since he didn't bear it so he can ignore the fact that it's related by blood, but the mother... dom!mom incest is almost like severely twisted masturbation, that kid's a part of you! Sorry to ramble, just trying to think it out.