For 2000 years in Europe, Jews have been an "other" and were kicked out of a dozen European countries at various times and told to go back to Palestine where they belong. Jews were the main target of the inquisition, the crusaders made sure they stopped enroute to kill Jews and so on. Being a Jew, every Easter accused of killing christ, facing pogroms etc- with a religion that didn't try to convert anyone- do you honestly think people were lining up to convert to Judaism?

European Jews have specific genetic diseases because they intermarried so much within their own local communities- which is why every Jew today is 5th/6th cousin or closer. Occasionally a Jewish man would marry a woman who converted, which is fine under our Jewish tribal law. This would not happen often- as most Christian fathers would be horrified to have their daughter marry a Jew. Still, over 2000 years, plus various rapes that occurred in pogroms, European DNA joined the Jews living in Europe. This is not eugenics or about pure-blood nonsense. Admixture occurs, just like Jews in Arab lands would have some of that DNA too. Does not make either less Jewish, or less linked to the land they prayed each day to return to.

My family were late to leave, fleeing a pogrom in Hebron just 500 years ago. We moved to Beirut first then onto what became Prussia. Eventually Australia.