First of all...
due to foster care and adoption, you can say I only half-grew up with my brother. But even after not speaking for years, meeting up with him as an adult, I have no physical attraction to him whatsoever. I love him dearly, but not that way. So the incest thing being just from growing up... no true in this case.
Next- I would find it very hard to accept if my adoptive mother would express interest in camming. She's been a one-man girl all her life, so I would hardly expect her to start now.
My biological mother might be dead, but if she weren't, it would still be shocking to me. Mostly because of how hardcore Christian she was (the good kind, you know, the kind who believes that Christianity is all about loving everybody)