Mary’s perpetual virginity has been Christian teaching for two thousand years. She and Joseph did not have children after Christ. Scriptural reference to Jesus’ “brothers” could mean cousins or Joseph’s children from his first marriage. The original Greek is not the same as our English word “brother.”
See, for example:
http://www.goarch.org/ourfaith/ourfaith9174
http://www.oca.org/QA.asp?ID=204&SID=3
WRONG.
The bureaucratic political powermongering elites of the club in Rome cleverly capitalized on some traditions some Christians were fond of 300 or so years after Christ.
However, startlingly, most of the Marian heresies were not very formalized until the modern era.
IIRC, —many even in the last century.
Incredible.