... which means any attempts to view ladies changing is going to have to involve a little more planning, or, like, an Internet connection.
The basic biological nature of childbirth presents certain advantages in determining maternal parentage. If it came out of you, it's yours, and aside from a few exceptions (surrogate pregnancy, and also if everyone's giving birth in this one big darkened room), it's a pretty easy rule to work with. But the same doesn't hold true for fathers, who, until the invention of Maury, could never be 100 percent sure of their paternity.
And it's this foundation on which the Milkman Joke was laid. (Boom, word play.) You see, back when people didn't have refrigerators, dairy had to be delivered fresh by door-to-door milkmen. And as this was the same time when men were expected to be out of the house and women expected to be very much in it, there was an awful lot of unsupervised contact going on between married women and strange, milk-scented men.