When did folks first start believing that Mary had other kids? When did the first Reformer deny that mary was a perpetual virgin? And who was it? Are there Protestants who still believe that she was a perpetual virgin?
Freegards
That’s OK.
The entire “virgin” birth, let alone forever-virginity, is no where in Jewish tradition.
It’s merely that the Messiah would be (will be, if Jewish) born of a “very young woman” to be literal about it.
(A virgin birth is not contradictory per se, IMHO, but not easily consistent with the royal line of David, as that is paternal. Regardless, it’s just not the Jewish tradition of the Messiah.)
“When did folks first start believing that Mary had other kids?”
Based on the Gospels, I’d say around 5-10 AD...
Actually I know some never did.