According to a British geneticist who was on the Discovery Channel, a virgin birth, although it would still be a miracle, is consistent with known science!

His logic was:

1. Parthenogenesis, where a mother produces an egg with a genome identical to hers, is possible. It happens in many lower animal species, like rotifers. No male gamete is necessary.
2. It is theoretically possible for a human to produce such an egg cell, although extremely unlikely.
3. Since Mary was a female, but Jesus was male, Mary must have had a Y chromosome. This is extremely unlikely, but possible--there are women who have one X chromosome and one Y chromosome, but they develop as women. Something along the chain of what causes the presence of the Y chromosome to lead to male characteristics is broken.
4. XY women usually do not have a uterus at all, let alone a functioning one . . . but it is still possible even if extremely unlikely.
5. Jesus could have been born of a Virgin Mother who happened to be XY with a functioning reproductive system. It's still a miracle of course, because such an unlikely event was coordinated in God's plan along with other events necessary for the salvation of mankind.

Maybe we'll see this in the next Papal encyclical . . .