Why did Christ have to be born of a virgin?

Les explains that the physiological makeup of the woman's reproductive system shows the fetus in the mother's womb never receives any of the mother's blood; the blood comes from the father. Therefore Christ, as the seed of the woman, had to be virgin born; otherwise the blood would have come from a human father, which would have tainted His divine ability to die for the sins of the world. His blood came from the Father, as does every other creature that is reproduced. Les also notes that veterinarians at Colorado State University proved even in cattle none of the blood of the mother cow ever courses through the fetus; the blood system comes from the sire. This is all part of God's intrinsic plan of getting ready for the virgin birth, so that Christ's blood was divine because it came from His Father, who was God Himself.