All, I can say is, well we are all different, aren't we?
As children my sister and I cleaned our teeth at the same time at the same basin, and weed in each other's presence without embarrasment, as our house only had one bathroom and we had to be out of it, before Daddy needed it, as, like most men, he took an inordinate time shaving!
On rare occasions when a school-friend slept at our house, she and I would wash at the same time -she had been plonked in one end of the bath and her brother in the other until they were about seven - I had at the same age, shared the bath with a little boy my parents were fostering. No-one thought that odd.
My mother bathed, dressed and undressed with both of us girls. Even after we were both grown up this felt perfectly natural when we were in the same house.
My father, on the other hand, never was seen naked by my sister or myself, and when in his old age, he needed help bathing, it felt more natural for my husband to help him, until we had fixed up with the district nurse that a carer would come in to make sure he did not fall in the bathroom.
DH and I bathed together and in the last month of his life when he could not manage alone, I bathed him and wiped his bottom when necessary too, plus emptied his urinal.