A second objection to Mary's virginity arises from the use of the word, heos, in Matthew's gospel.
Matthew 1:25
He (Joseph) had no relations with her until (heos) she bore a son, and he named him Jesus.
The Greek and the Semitic use of the word heos (until or before) does not imply anything about what happens after the time indicated. In this case, there is no necessary implication that Joseph and Mary had sexual contact or other children after Jesus.