Does Kelly have siblings?
If not, the case for poor parenting gains in probability.
Sometimes even the best of parenting does not produce positive results with some children. Reaching the child just may not be possible. I’ve know parents who have these kinds of children, and they were great parents. The child was just a mess though and nothing they tried proved to be successful. Usually they have some kind of mental problem that keeps them from feeling any empathy whatsoever, even though they outwardly appear to be somewhat normal.