Grandparent Sexual Relations Toward His Own Grandaughter

So, I've been watching Dr. Phil house where hes trying to talk to people and help them out and I've only got to see some episodes but not very much. Well this one that I saw was a 60 year old something grandpa who happen to have sexual relations with his only grand daughter. And the little kids parents didn't know what was happeing until she didn't want to go to their house anymore and the little girl did tell the grandmother and oh my gosh she told her no its not going on and he's not like that. And then the grandfather was like Satan made me do it and plus I haven't had a good Christian walk or something like that also pointed out that he didn't know it was wrong to do that. I was like oh my gosh this dude is sick and is not a very good grandfather and he ought to know better and is bad and he should have a lot more since than that. I don't know but when I heard this I was like you such an idiot and a really sick guy and as for the grandmother she should have listend to her grand daughter and helped her out but no she didn't do a thing but just kept quite about it. I mean that is so wrong to do that especially to family memembers and its wrong period and really stupid and pointless and no one should have to go through that.