When they are no longer comfortable with it. My 7yo son and 6yo daughter will still hop in the shower together if we let them. My almost 3yo daughter takes showers with anyone (her brother, older sisters, me or daddy).
The only reason we made them stop bathing together is that our tub is cracked and they were jumping around and making it worse (we had water leaking/gushing into the room below). Otherwise they's probably still bathe together.
As it was tonight as my 8yo dd got out of the shower my 7yo son came running in stark naked, covering just his privates. She just laughed and hugged the towel tighter and tried to squeeze by him without touching, lol. She won't bathe with anyone but the 2yo but changes in front of her brother and sister (if she doesn't have to get completely naked). The older 3 share a room so they are used to being around each other.
at 10:34 PM on Feb. 22, 2009