You are wrong.
Could they have been adoptive brothers?
Can you cite a single person called "son/daughter of Mary or Joseph" aside from the Lord in scripture? (And by the way, this is a simple YES or NO question.)
I am not wrong. Look up the Greek. I did. Adopted brothers and sisters. Hmmmmm. Interesting possibility. Wasn't aware Mary and Joseph ran an orphanage. Maybe they were baby brokers.
And as far as being a son or daughter of Mary or Joseph, no I can't find that phrase. So I guess that means that they were neither and were part of Francis Crick's Panspermia theory. They were seeded here by Space Aliens.
You really are impossible!