From http://en.wikipedia.org/wiki/Lady_Janet_Stewart

Janet Stewart, Lady Fleming (17 Jul 1502 – 20 Feb 1562) served as governess to her niece, Mary, Queen of Scots.

• Parents: Illegitimate daughter of King James IV of Scotland with Isabel Buchan, daughter of James Stewart, 1st Earl of Buchan.

1. married Malcolm Fleming, 3rd Lord Fleming, even though they were related within a forbidden degree of affinity. After his death in 1547 ...
2. In 1548, liason with King Henry II of France. Their son, Henri de Valois-Angoulême (1551–June, 1586), was "the chief and most highly favored natural son of the King".

8 children of Lord Fleming and Janet Stewart:

1. Johanna, b. 1525.
2. Janet, b. 1527, m. 1st, John Livingston, eldest son of Alexander, 5th Lord Livingston and brother of Mary Livingston, one of the Queen's "Four Maries."
3. John, 5th Lord Fleming, b. 1529.
4. Bridget, b. 1530.
5. James, 4th Lord Fleming, b. 1534. His only daughter and heiress, Jean (1554–1609), would marry John Maitland, the younger brother of William Maitland, his sister Mary's husband. His grandson by Jean was John Maitland, 1st Earl of Lauderdale.
6. Agnes, b. 1535, m. to William, 6th Lord Livingston.
7. Margaret, b. 1536, m. 1st, to Robert Graham, Master of Montrose, by whom she had a son, John, 3rd Earl of Montrose; 2ndly, to Thomas Erskine, Master of Mar, younger brother of the 17th Earl of Mar, but had no issue; and 3rdly, John Stewart, 4th Earl of Atholl, high chancellor of Scotland, by whom she had three daughters and a son, John Stewart, 5th Earl of Atholl. Margaret Fleming was said to be a witch and to possess the power to cast spells.[2]
8. Mary, b. 1543, m. 6 Jan 1567, to William Maitland of Lethington.