ok this is what I always say on these threads - we have used willy for DS1 and DS2, struggled with name for DD3 - eventually ended up with 'bits' and 'private parts' - now use it for all three, interchangeably, eg in bath, "now, wash your private parts"
Quite like the recognition that these are your own private bits, without making an enormous hullaballoo about stranger danger - see this website
BTW my mother never called it anything. I knew what a vagina was, but there is no equivalent of the willy, until the MN fanjo usage becomes more widely acceptable.
Must go now, kids in bath washing whatever we all choose to call them