Luke talks about the virgin birth.
Luke 1:30
"Do not be afraid Mary, you have found favor with God"
NASB
Do you suppose Mary would have found favor with God if she had just married Joseph but had children from another man?
Why does this interest you so much?
That's a great question. It interests me because I'm saddened to see millions of people in Christendom who have their faith in a narrative and are fighting each other over the interpretation of that narrative. If God is the author of truth which I believe He is, and has made Himself known through out creation wouldn't it be more realistic to think He wanted all men to come to know HIM, NOT a book written about Him.