Anonymous wrote:What about the local Polish community?
Perhaps someone there can help him find more info
He most likely has more in common with them
Jews who lived in Poland would be unlikely to have much in common with their mostly Catholic Polish neighbors.
The best way for him to find information if he wants to find out if has Jewish roots is to do genealogy. He can look up a paper trail by starting with the information that he knows such as his grandparents' names. He can search for the Census records from 1900 - 1940 for free on familysearch.org or for a fee on ancestry.com. The Census from 1930 and earlier asks where the person came from and where (country) their parents came from and what native language they spoke. For Jews, it would likely say Yiddish, sometimes Hebrew. It will also give what year the person immigrated. From there you can search for a ship manifest for the ancestor which will sometimes list the town the person is from. And again would identify the person as Jewish usually by calling them a Hebrew rather than Polish. You might also find naturalization records which can give a wealth of information about from where the person came and there are other records, too. These would at least give him an idea if his ancestors are indeed Jewish. Of course, they could have been hiding it and lying on documents, so if it doesn't say Yiddish/Hebrew anywhere, that isn't proof.
Another option is to find death records for his ancestors. If they weren't hiding their Jewishness, you would generally find them buried in a Jewish cemetery and their gravestone would often be at least partially in Hebrew. There are also some records from Eastern Europe to be found. Depending on where his ancestors are from, some towns have more released records than others. They are still being released.
At the same time he is tracing the paper trail for his ancestors, he can do a DNA test with one of the big companies. After a few weeks, it will show if he has Ashkenazi Jewish DNA (they were an endogamous population - doesn't show if they were practicing Jews, obviously). It may also show up as Iberian which could indicate Sephardic Judaism (those from Portugal or Spain). The DNA will give him clues whether he has the DNA, but only the paper trail will confirm which line it comes from.
And while some people including OP might find it "weird" that her husband has this feeling of being Jewish, I have found that many people for some reason have feelings or clues that they are Jewish (or perhaps something else) and want to know more. Some people just have a strong desire to find out who they are and here they came from and those people generally pursue genealogy.
I highly recommend the book Turbulent Souls by Stephen Dubner (of Freakonomics fame). It is a wonderful memoir of Stephen's life growing up in a large, religious Roman Catholic
family but him feeling like there were secrets/clues in his family that he had a Jewish background. He investigates and questions his mom and other relatives and comes to find out that both of his parents were born Jewish but individually converted to Catholicism. Stephen somehow felt a deep connection to the Jewish faith and sought out how to become a Jew again. It is a great story and something it sounds like the OP's husband can identify with.
Of course, if OP's doesn't find any Jewish roots, he is, of course, still welcome to explore the Jewish faith which could lead to conversion if he's interested.
Best of luck!