A fascinating, thoughtful, moving piece. My mother had a similar experience rediscovering her Jewish roots years after my grandmother (a German Jew) fled Nazi Germany and essentially did what it sounds like your father did, by burying her Jewish heritage (she married an Englishman, and none of her traditions were passed down, perhaps understandably given her her atheism). My mother (who married a Scotsman, my father) has since retraced her family history. We have surviving relatives in various places, but also a lot of family that died in the Holocaust.