Atheist Memes

No, not really. The info is sparse, but she must have been at least 14.

Many Christians believe so and have for a very long time:

The Protoevangelium of James, an extra-canonical book, has been the source of many Orthodox beliefs on Mary. The account of Mary's life presented includes her consecration as a virgin at the temple at age three. The high priest Zachariah blessed Mary and informed her that God had magnified her name among many generations. Zachariah placed Mary on the third step of the altar, whereby God gave her grace. While in the temple, Mary was miraculously fed by an angel, until she was 12 years old. At that point, an angel told Zachariah to betroth Mary to a widower in Israel, who would be indicated. This story provides the theme of many hymns for the Feast of Presentation of Mary, and icons of the feast depict the story.[178] The Orthodox believe that Mary was instrumental in the growth of Christianity during the life of Jesus, and after his Crucifixion, and Orthodox theologian Sergei Bulgakov has written: "The Virgin Mary is the centre, invisible, but real, of the Apostolic Church.

https://en.wikipedia.org/wiki/Mary,_mother_of_Jesus