She had five siblings, including James III, who ascended the Scottish throne in 1460 upon their father's accidental death by an exploding cannon.
Mary was married to her first husband, Thomas Boyd, Earl of Arran, when she was thirteen years old, before 26 April 1467.
Mary, upon hearing that her husband was to be summoned before the king and Parliament to answer the charges, immediately went to the harbour of Leith when Thomas' ship docked in July, to forewarn him.
Upon her arrival in Scotland, her brother James detained her in custody at Dean Castle in Kilmarnock, until her marriage was annulled.
Due to their proximity to the throne, Mary's descendants, the Hamiltons of Arran and the Stewarts of Lennox, would obtain considerable power, and play conspicuous roles in 16th-century Scottish politics; especially affecting the life and reign of Mary, Queen of Scots, the great-granddaughter of her brother, James III.