This quote might also explain- sending him off to College- which is similar to what happened when he was sent to school in England:

History of Nairnshire
By George Bain, 1893

Alexander, the young Laird of Brodie, Lethen's nephew, who became Lord Brodie, had been sent into England when eleven years old for his education, and returned in 1632 on his father's death, and by special dispensation from the Lords of Council was declared of age (he was but nineteen years), and served heir to the estates in 1636. While yet a minor, he married Elizabeth Innes, widow of John Urquhart of Craigston, Tutor of Cromarty, and daughter of Sir Robert Innes of Innes, by Lady Grizzel Stuart, daughter of James, the Bonnie Earl of Moray.

Richie