Source Descendants of Adam de Carey, Murray W. Oltman:
Thomas Carey was half-brother to Robert Carey. He did not inherit his father's property, but married Margaret Spencer. From this marriage sprang three royal lines. They had two sons- (1) John, Knight, born 1495, the ancestor of the Falkland Line; (2) William, born 1500, was the ancestorof the Baron Hundson and Monmouth lines. William was Knight of Cockington and married Mary Boleyn, sister of Anne Boleyn. William's son, Sir Henry Carey, born about 1525, was Lord Chamberlain to Queen Elizabeth and was also her first cousin. This is because even though William was publicly declared his father, in fact Henry was sired by King Henry VIII, issue of his affair with his wife Anne's sister. In 1561 Henry was appointed a Knight of the Garter, which was founded in 1348 by Edward III; the Garter was England's highest and most coveted order of chivalry.
Note: This Thomas, born 1500, is cousin to Thomas, son of Robert, and they were born in the same year.