Smoke
Done here.
Well, seriously, do you really think there was no doubt?How about to insure that there was no doubt about Joseph not being His father.
I mean, assuming that Mary told all her friends and neighbors she was a virgin, and assuming that Joseph backed her up, do you really think all the friends and neighbors believed it? Would you believe it? Matthew says that the neighbors called him "the carpenter's son." (Mark says, "the carpenter, the son of Mary," and I've heard some people claim that this, in conjunction with Pharisees' retort to Jesus, "We were not born of fornication" indicates that the neighbors thought Jesus was a *******. But I think it's more likely they just thought he was Joseph's son.)