[user104658]

To be fair, in these situations grandparents do need to be assessed in exactly the same way as any other care arrangement before getting custody of a child. That's because if there are major issues that mean a child can't stay with a parent... A large percentage of the time, there will also be issues in the grandparents home life too. Obviously not always, some people fall into a bad lifestyle for other reasons, but the vast majority of the time if you want to figure out the source of a person's deep personal issues you don't have to look much further than their own parents.