User blog comment:D. Cello/Assassinews 10/11 -- Desmond's Ancestry Revealed/@comment-58.170.127.164-20111016223229/@comment-1153722-20111016225215

No. Nothing in the games says so.

Only thing that made us believe they were related in the first place, was Patrice Desilets saying so in interviews he gave before AC2 came out.