"Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost. Then Joseph her husband, being a just man, and not willing to make her a public example, was minded to put her away privily. But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife; for that WHICH IS CONCEIVED IN HER IS OF THE HOLY GHOST."
The Bible teaches that Jesus was a sinless man. All men are born with Adam’s sinful nature and are, therefore, subject to the curse and eternal death. Jesus was without sin and, therefore, deathless until He took the sin, of others, upon Himself, to act as a substitute to fulfill God's words (The wages of sin is death). Now while Jesus was of Adam's race, according to the flesh, He did not inherit Adam's nature. This alone will prove that sin is not transmitted through the flesh, but through the blood. Even though Jesus was of the seed of David, according to the flesh, this could not make him a sinner.
It is, now, known that the blood which flows in an unborn baby's arteries and veins is not derived from the mother. It is only after the male element has entered the ovum that blood can develop. The female egg does not contain the elements essential for the production of blood. The mother's blood is only used to transmit nutrients and waste to and from the unborn baby.
Sinful heredity is transmitted through the blood and not through the flesh. Even though Jesus received His flesh from a sinful race, He could still be sinless as long as no blood, of this sinful race, entered His veins. God must find a way for Jesus to be perfectly human, according to the flesh, but not have the blood of sinful humanity. That was the problem solved by the virgin birth. Unlearn.