George (Hungarian: György) was illegitimate son of Andrew I.[1][2] George was the son of a non-Christian marriage of Andrew I, to a Hungarian woman, before Andrew's conversion to the Roman Catholic faith, but subsequent Christian marriage to a Russian Orthodox princess rendered the non-Christian children of his first marriage illegitimate under Catholic Canon law, and therefore with no rights to the now Christian Hungarian throne. George went to Scotland in 1055 and became ancestor of the Drummond family.[3]

http://en.wikipedia.org/wiki/George,_illegitimate_son_of_Andrew_I_of_Hungary

According to E.S. and other sources,[4][5]George was the son of a non-Christian marriage of Andrew I of Hungary, to a Hungarian woman, before Andrew's conversion to the Roman Catholic faith. Andrew's subsequent Christian marriage to a Russian Orthodox princess rendered the non-Christian children of his first marriage illegitimate under Catholic Canon law, and therefore with no rights to the now Christian Hungarian throne. Consequently, George was obliged to leave Hungary, settling in Scotland, and founding the Drummond family, possibly named from the lands of Druiman which were granted to him either by MacBethad, or Malcolm III of Scotland. His choice of Scotland was very likely linked to the exiled English Royal House, since they had previously resided at the Court of István (Stephen I), King of Hungary, and after the submission of Harold II of England to William the Bastard, Duke of Normandy in December 1066, arrived in Scotland where they were warmly received by Scotland's King Mael-Coluim III who married Edgar's sister Margaret in 1070.
http://en.wikipedia.org/wiki/Drummond_family