constantine was born in new york city into the house of sidamon-eristavi, claiming descent from the medieval kings of aragvi. he was the son of prince simon sidamon-eristoff, a georgian military officer, who emigrated to the united states after the bolsheviks invaded georgia in 1921, and anne tracy, a descendant of john bigelow, an american diplomat in the mid-19th century. in 1957 he married anne phipps sidamon-eristoff, a granddaughter of andrew carnegie's partner, henry phipps.