And as long as mother & son or father & daughter, don''t procreates then it''s no harm done, from a biological standpoint. As adults it''s there right to do so, and the state legislation should not prohibit it. Adult Incestuous relationships is a natural and rightful as homosexuals. I was abused too by the father of my father. A story very similar to yours. Since I was 5, that''s as early as I remember, until I was 10. I also felt uncomfortable and told my mother, who said: You must have misunderstood him.