this suggests there is evil intent. As I was saying here, the plain translation of the word עלמה in Isaiah 7:14 is not a virgin but "the young woman". so, understandably the rabbis interpret the prophecy (that was told 700 years earlier and a context that makes you rethink whether it talks about the Messiah) as the plain translation. for a detailed explanation
click here
as I understand, the angel Gabriel told Josef that Mary the child is God's son and he is the one who impregnate her. imagine Josef telling this to other people... it means that Christ grew up as a ******* in other people's eyes.