Why does incest destroy some and bounce off others?

I doubt very much that incest "bounces off" anyone. But, as with any emotional damage, partial or full recovery depends on the "victim" taking responsibility for their own recovery. People who take responsibility for their own recovery usually end up as emotionally strong people who can help themselves, help others and stand up to the people who commit these "crimes". But, why are some people able to take responsibility for their own recovery and other not? Perhaps it depends on the severity of the emotional damage incurred, perhaps it depends on the degree to which the "victim" looks around for help (because there is help available if you can find it), and perhaps it depends to some degree on the luck of finding the right kind of help at the right time.