George was born about 1636, probably in Paisley, Scotland, as the third son of James Hamilton and his wife Katherine Clifton.
George's mother was Dowager Duchess of Lennox from her previous marriage and Baroness Clifton of Leighton Bromswold in her own right.
[7][8][9][d] In 1649 his father was excommunicated by the General Assembly of the Church of Scotland as a Catholic and ordered to leave the kingdom.
[11][e] His two elder brothers grew up to reach adulthood but predeceased his father, making him the only surviving son and heir.
The title passed to the nearest cadet branch which was that of the barons Hamilton of Strabane, who descended from his uncle Claud.