The gene for lactase persistence evolved in one person thousands of years ago possibly either a yamnaya or an Anatolian Neolithic farmer. That gene then was selected for because it provided an advantage (the ability to digest milk in an age without refrigeration or water purification was obviously good). Because jews are so inbred all it should have taken is one person a few hundred years ago in the Jewish community to have acquired that gene from a non Jewish ancestor and it should have spread among them all within a few hundred years. That’s how other isolated communities like the Irish and the basques and the icelandics developed lactase persistence in such high numbers. One random guy in their community is lactase persistent and within a few hundred years he’s the ancestor of everybody in that community many times and therefore that gene is in everybody lol.
Lactase persistence is also a dominant genetic trait. If you have one lactase persistan gene and one lactose intolerant gene you should be lactase persistent.
Jews however have not only repelled that gene, they are the most VIOLENTLY lactose intolerant group. You give a Chinese person or a black or an Arab a milk drink and if they’re lactose intolerant they might get stomach pains. The Jew on the other hand will become violently ill almost like they’re allergic to dairy or cream. Why? All it should have taken is one Dutch, German or Polish ancestor who was White hundreds of years ago and they should all be able to drink milk. It’s really weird.
Yeah but all it takes is one non Jewish ancestor from a Northern European country and they’re lactase persistent. If a White person from Ireland or Britain (the most lactase persistent countries) was to have a child with a lactose intolerant Ethiopian, the mutt child would be lactase persistent because they’d have one lactase persistent gene and one lactose intolerant gene from each parent and lactase persistence is dominant. Because of how small Jewish bottlenecks were, there were a lot of non Jews in their ancestry too. This is especially the case with Sephardim who were less hostile to integrating others than the more neurotic askhkenazim. And yet they don’t have the ability to digest it.
Other bottlenecked cultures like the Irish got the lactase persistence gene because over generations the minority of people who had it originally ended up being the ancestors of everybody through there being a small population. Now pretty much everyone there has it. This is how other mutations that developed in a single person thousands of years ago manage to spread- blue eyes, left handrdness and red hair are great examples (and red hair is actually common in Jews, although with Jews it’s normally the darker red- the auburn or chestnut color- whereas with actual White people it’s normally the orange/ginger color). The inbred population keeps these single ancestor mutations alive in a way that a far more diverse founding population doesn’t.
So what I’m saying is- a single prolific non jewish ethnic person who converted to be a jew or integrated with the jewish community and had children with them should have resulted in modern Jews being lactase persistent because their genes should have been spread out among the tiny isolated population easier than a more open and diverse population elsewhere.