Mary, the mother of Christ, was born under the Law of Moses. She had to be tainted with sin because the law could not save us, so did she ever tell a lie,or think a bad thought? If so she sinned, and Christ was tied to her imbiblical cord, so the sin nature was passed on to him.
Sin is not a communicable disease. "The soul who sins shall die. The son shall not bear the guilt of the father, nor the father bear the guilt of the son. The righteousness of the righteous shall be upon himself, and the wickedness of the wicked shall be upon himself" (Ezekiel 18:20).