Not sure where to ask the question, Mods please move if there is somewhere more appropriate.

DSS is 10 years old and lives most of the time at his mums (he is with us every other weekend plus 1/2 school hols).
he adores his little sister, Molly Jane, and wants to be involved with everything when he is with us.

We let him bath her a couple of weeks ago - as in both in the bath together, but a couple of people raised their eye brows at us when they were told.
Is this wrong?
He is aware that both his Dad and I will bath or shower with Molly Jane. He still sees his Dad naked at times but not me anymore (that stoped only when i was pg thou), he would see there being no difference.
He is not sexually aware yet.. and to be honest i hadnt even hough of it in that way and am saddened that i am having to ask.

Advise please - anyone else had a similar situation? I think had DSS been a DSD i wouldnt have had raised eyebrows

Thanks