User blog comment:Ivan-G-D/Golden 200 Members + Self-Impregnation/@comment-86.130.13.228-20110720072453/@comment-4125089-20110720100329

Well, when two non-green people have kids, it is possible that their kid is green, if one of the grandparents is green. ;)

When a child is born, it gets genes from both the parents and the grandparents (but not the great-grandparents and so on), so it's likely to end up with a green skin, even though its parents don't have it. You can check in the main tree, that the girl (who are you watching as the mom) has a green mom (so the grandma has the green skin gene). ;)

As for the generations, 7 main ones, plus many mid-generations. :)