My wife was a “big sister” for several years to a “problem mother”. The little sister was living with her grandmother. Grandmother would help the mother any time she needed it, but the mother being into meth and all sorts of other drugs was a challenge. But grandmother still helped her.
That is, until a year ago, when the mother died of a drug overdose.
And the “little sister, who is now 14, is making terrible decisions. No matter how we tried to help her make the right decisions, grandmother would both enable her and fight with her as though she was a peer. It is a terrible situation being passed down from generation to generation. I’ve made the decision that this girl is dangerous to my wife and me. I was always careful to NEVER be alone with this girl, for MY protection.
Sadly, very, very true. I know from personal experience of what you speak and it's one of the reasons my ex wife is now my EX wife. Generational problems such as drug use, physical abuse, sexual abuse (of which my ex wife suffered from) and the horrific damage they do from one generation to the next is really staggering. It's not just the kids either, it affects grandchildren, great grandchildren etc..
My own two sons know my ex wife isn't quite right in the head, they don't know why yet. She has almost no relationship with our oldest son. He was home from college for the summer and lives with me. She saw him for a whopping five hours all summer. I can see the hurt in his eyes when he comes back from seeing her yet he goes to see her because that's his mom. He knows when he needs help he cannot call her -- he calls me.
Same with the youngest son who also just entered college.
As angry as I am (still....) at my ex for how she destroyed our family literally on a whim of hers, it's sad to see what she's become and it breaks my heart to see the impact on my two sons. Some people say "well, they're adults - they understand" but no they don't. They see a dad who did everything he could to hold it together while mom was hell bent on ripping things apart.
One day they'll know the truth, I suppose when I think they're ready to hear it (or they ask...) and hopefully that breaks the chain.