Jesus was not born with original sin. His Father is God; His mother is the immaculately conceived and sinless Mary. There’s no sin to be passed on to Him.
Yes, Mary could have sinned. If even Jesus was tempted, surely the human Mary was also. She is often referred to as the “Second Eve,” meaning that she was not born with original sin and had free will, just as the first Eve did. The original Eve failed the test and used her free will to sin; Mary did not.
Catholic doctrine teaches that Christ was without sin of any kind, and that He was absolutely incapable of sin; that necessarily follows from the fact that He was truly God, and could never cease to be God.
The Gospels present our Lord as a flawless character, supremely pure and holy, with no consciousness of sin, speaking no words of repentance and seeking no forgiveness. Jesus is the Saviour of sinners, not one of them. He could say to His bitterest enemies, “Which of you convicts me of sin?” (St. John 8:46). It was predicted prior to His Holy Natavity that “…he will save his people from their sins” (St. Matt. 1:21). Under the inspiration of the Holy Spirit, St. Peter stated in his first Epistle that “He committed no sin” (I Peter 2:22). St. Paul, writing to the Corinthians, wrote that He “knew no sin” (2 Cor. 5:21) and St. John did not hesitate to say in his first Epistle that “in him there is no sin” (I John 3:5).
It is true that many liberal Protestants disavow the divinity of Christ, believing He was a mere man, albeit a very good and noble man - even a teacher of the most superlative ethics the world has ever known. Having thus dragged our Lord down to a merely natural level, they unblushingly still call themselves Christians!
As regards the Blessed Virgin, "In consequence of a Special Privilege of Grace from God, Mary was free from every personal sin during her whole life. (Sent. fidei proxima.)
The Council of Trent declared: “No justified person can for the whole of his life avoid all sins, even venial sins, except on the ground of a special privilege from God such as the Church holds was given to the Blessed Virgin”. Pope Pius XII says in the Encyclical “Mystici Corporis” of the Virgin mother of God, that: “she was immune from all sin, personal or inherited”" (Fundamentals of Catholic Dogma, Ludwig Ott, Tan Books and Publishers Inc. 1974, p.203)
Trust that this will help to clarify things for you a little.