I understand the study's basic methodology. It doesn't change my point. And I don't know that it's never going to be provable. Maybe with enough data we could find a very subtle pattern that proves it. The point is, this study doesn't, nor do any of the others on their own, but they collectively provide evidence that the hypothesis may be true.
No, I'm not. Ironically, I think you are. But I'm tired of debating this with people. It says it in the linked article. Debate with the authors of the study if you want to.