Luke 2:33 as translated in (RSV) says:
And his father and his mother marveled at what was said about him.
Seems like mentioning (father) in the RSV translation could cause confusion with the idea of the Virgin birth.
Whereas the same passage - Luke 2:33 as translated in (KJV) says:
And Joseph and his mother marveled at those things which were spoken of him.
No confusion in KJV translation.