When Lady Maria Margaret Sinclair was born about 1263, in Caithness, Scotland, United Kingdom, her father, Sir William VI Sinclair Baron Laird of Rosslyn Sheriff of Edinburgh, was 33 and her mother, Matilda de Orkney, was 22. She married Sir, "The Patriot" Simon Fraser III about 1299, in Scotland. They were the parents of at least 4 sons and 2 daughters. She died in 1364, in Peebles-shire, Scotland, at the age of 101.