You got that one right.
I've heard Catholics make the connection between Mary being sinless and that's the reason she had to be perpetually virgin, as if having sex with her husband was sin.
But as we both know this idea of Mary remaining a virgin is blown away in Galatians 1:19 where Paul writes:
But I did not see any other of the apostles except James, the Lord's brother.
Paul wouldn't make a mistake of calling the brother of Christ a cousin. He was too good of a writer and knew his Greek well. It's amazing how Catholicism falls apart under the light of Scripture.