Are genetic tests able to determine exactly in which family line the genetic mutation originated? I am diagnosed Celiac, and believe that my father (an only child, surname Hetherington,), his mother(Williford, only sibling of 4 to have a child), and his mother's sister (no children) all had the disease or related complications. My great grandfather (surname Williford) was the only child from his father's (my gggpa) second marriage (maternal surname Pearson/Pierson). They are all long deceased and I am the only living individual from this line. None of my Hetherington line first or second cousins has or had symptoms of the disease. I'd like to know if the mutation was from my ggpa's paternal or maternal line, or if somewhere in my lines two carriers of the gene were the source. My paternal lines are from Ireland, Scotland, and Germany. I can find no evidence of symptoms or the disease on my maternal side. I have done DNA testing for genealogy but not for genetics. I am going to cross post this on the DNA board. TIA!