Mary?
The 'wife' of frustrated Joseph?
The Lady of the Perpetual Headache?
Of course, Mary's perpetual virginity is just another misconception of the RCC. Scripture tells us that Mary and Joseph had sexual relations: When Joseph woke from sleep, he did as the angel of the Lord commanded him: he took his wife, 25 but knew her not until she had given birth to a son. And he called his name Jesus. (Matthew 1:24, 25)
There is absolutely nothing immoral, impure, sinful, or improper with Mary having sexual relations with her lawful husband. It shouldn't be at all surprising that Jesus would have brothers and sisters when his parents are having normal marital relations.