The son of Robert Arbuthnot, 2nd Viscount of Arbuthnott by his second wife Katherine Gordon, Alexander married Jean (d. 22 October 1746), eldest daughter of Sir Charles Maitland, Bt., of Pittrichie in Aberdeenshire, heiress to her brother Sir Charles Maitland, Bt.
The son of Robert Arbuthnot, 2nd Viscount of Arbuthnott by his second spouse Katherine Gordon, Alexander married Jean (d. 22 October 1746), eldest child of Sir Charles Maitland, Bt., of Pittrichie in Aberdeenshire, heiress to her brother Sir Charles Maitland, Bt.