That’s the appeal of it, of course. There isn’t a definitive study. There can’t be.
Even if we created a forty-year-long, double-blind twin study, there’d be room for someone to ask “what about?…”
It doesn’t matter that the peer-reviewed and consistent results we have are clear to those who read them with an open mind.
The attraction of simple stories about complex phenomena is that we get to make them up and imbue them with whatever reassurance, solace or threat we choose. Human beings didn’t evolve to be rational decision makers. We’re creators and consumers of stories, seeking status and affiliation, and prioritizing short-term feelings over long-term evidence.
It’s nice when a story that’s precious to us is reinforced by evidence, but it’s rarely essential. Belief isn’t dependent on facts, that’s why we call it belief instead of facts.
It’s helpful to wonder who benefits from sharing a particular story with us, and what it costs us to believe it.