No Great President has ever had difficulties with their children, never... /s
http://en.wikipedia.org/wiki/Patti_Davis
You're right. But, personally, even as an adult I would have a real hard time with my dad and stepmom if my dad cheated on my mom with her. I absolutely cannot stand cheating. You're not happy, get a divorce, the family will survive. Outwardly cheating and then announcing the divorce at a press conference is another matter. Can't say I blame the kids. Even before the presidential run I thought it was a totally classless act.
Besides Patti Davis, there're also FDR's five children.
Eleanor and Franklin's offspring were so messed up by their detached father and mother that they grew up to have, what, 20 divorces or something amongst them all?