This can certainly apply since the rise of hospital births (how do you know that you're not a mix-up baby?).

Also, surrogacy has always been possible -- even before the rise of artificial insemination techniques. Weren't there rumors that Prince James Francis Stuart was not the biological son of Mary of Modena but rather, the child of a peasant woman who had smuggled her infant into the delivery room?

This led to the practice -- now discontinued -- of witnessing royal births in Great Britain. It's not necessary in any case, since doubts over maternal or paternal identity can be resolved through DNA testing.