It's a bit of an old story, but a heartwarming one. The Polish hero Magdalena Grodzka-Guzkowska, who took part in teaching Jewish people in wartime Warsaw how to pass off successfully as Catholics among many other heroic acts, discovered her own Jewish roots many years later.
As the article says:
The discovery of Jewish roots is a growing phenomenon in Poland, where increasing numbers of Catholic or secular Poles in recent years have learned, often from deathbed confessions or from chance discoveries of documents, that they are of Jewish descent.
The Jewish revival in Poland is supported by all main political parties, and it is clear that the Jewish heritage of Poland should not only be mentioned, but should be considered a key component of Polish history. Many of us support Jewish causes, and the strong Jewish influence on Polish business and political life should not be understated.