@Geth:

And a parent who showers with a child is not necessarily getting off on it either. I'd say probably not. But the reason a lot of them don't do that is because if an 8-year-old were to go to school and say "Oh I shower with my mom/dad and we are all naked in there", that the reaction they'd get is one that assumes it would be sexualized.

We live in a society. It is not just whether it is sexualized for this mother and for these children. They are exposed to other people too. Plus, when the child is sharing the breasts with dad, she is not just learning that breasts are the way a mother nourishes her children, she is also learning that breasts are something her father gets off on sucking. Either that or she is assuming her mother gave birth to her dad too, which is even ickier than the other possibility. So it is impossible to make a "it is not sexual" argument here when the kids see the same "non-sexual" tits being sucked on by dad.