that's a bad attitude to take and leads to a lot of unnecessary guilt about something you have little control over. parents cannot do much to shape the personality and ability of their children in adulthood.
Guilt is unnecessary, agreed. And so is blame. Taking responsibility is. Without, you can't fix your mistakes.
And yes, personality and ability of children are definitely shaped by the parents. Of course, now that the kid is an adult, things are much harder to fix. But that doesn't mean the parents have no role in it.