On a separate piece of paper, draw a simple family tree for a couple showing children (F1), and lineages from two children showing grand children (G2), great grandchildren (G3), great great grandchildren (G4), and great great great grandchildren (G5). For the basic family tree, assume generations are outcrossed to non-related spouses. G5 relations between the two
Lineages would be 3rd cousins.
Assume that one of the couple is a carrier for a genetic disease. What is the chance that if a pair of cousins from each generation is carriers, and if they were to marry, what is the chance that a child born to them is affected?!