Reading into that quite a bit, I would say.
Luk 1:34 "How will this be," Mary asked the angel, "since I am a virgin?"
Mary was a virgin prior to giving birth to Jesus, but she no longer was after Joseph and she began with the 1/2 brothers and sisters.
Mat 13:55 "Isn't this the carpenter's son? Isn't his mother's name Mary, and aren't his brothers James, Joseph, Simon and Judas?
Did Mary immaculately conceive James, Jospeh, Simon, and Judas.
No, because she didn't conceive them at all.