I ran into some very funny ideas when I was looking into Asatru aka the religion of the Vikings. It’s reconstructed due to the invasive crazies calling themselves Christians (study history the thought of not converting by the sword was thoroughly ignored) but that is another point for another day.
What I ran into was that there is a theme of genetic ties to the religion, tracing back your bloodline to show you’re ‘allowed’ to worship. I find this rather silly because you know when all those ships were out raiding, trading, and doing mercenary work they didn’t consort with local women at all. Nope, not a one of those men had any children with anyone but their significant other or future significant other so obviously not being from one of four accepted regions would completely invalidate your faith. In this vein of thought Irish people could only be druids, Mexicans would have to worship the Aztec gods, and Italians would be praying to Zeus.