“I predict a future President of the United States will be a descendant of Abraham Lincoln, born in Bowling Green, Kentucky with blue eyes, but his parents will take him to Canada for a couple of years, then settle in Columbus, Ohio.”
What impact would such a prediction have on you if it had been made in 1860 and came true in 2014?
That is just how precise the prophecies about the birth of Jesus were. Isaiah, writing 700 years before Jesus, along with Micah and Hosea, predicted "the future Messiah would be a descendant David, born in Bethlehem to a virgin, would escape with his parents to Egypt, then settle in Galilee."
Unlike a lot of things where the more we know the more doubtful it becomes, when it comes to Jesus the more we know the more believable it becomes.