I have Margt d/o Wm Fargher + Jane Gell bapt at St Marks

tho Margt + George married in 1849 and he died 1853 and buried in Malew I can't see them in the 1851 census

I can't help with the genetic query except to point out the easiest genetic test is for descent in the male line which is blocked by your relationship being by a daughter - thus your links may involve genetic fragments that only vary slowly over time.