Or with the popularly vilified Rothschild family: The Rothschild males started intermarrying around the 1920s. Almost no one in that family today in Jewish, though they still carry the name.
This kind of thing always gives Jews the heebie-jeebies, but the truth is that a very evil Jew-hater descending from a Jewish ancestor isn't anything new.
In Parshat Lech Lecha (Genesis 12:1-17:27), we meet our future genocidal villain, Amalek, for the first time. Amalek's mother is Timna, sister of Lotan and daughter of Seir -- and a princess to boot. Seir descends from Chor, who I'm pretty sure descended from Canaan, who descended from Cham (via another ancestor because Chor isn't listed among Canaan's direct descendants).
But Amalek's father is Eliphaz.
Eliphaz's mother is Canaanite (Cham), but his father is Esav. Esav is the son of Yitzchak Avinu and Rivka Imeinu.
Eliphaz is half Shem and half Cham/Canaan.
This makes Amalek one-fourth Shem and three-fourths Cham/Canaan.
Amalek's paternal great-grandparents are Yitzchak Avinu and Rivka Imeinu, some of the greatest tzaddikim who ever lived. They're bona fide Jews.
Millennia ago, Jewish Sages already delved into how such great & spiritually pure people could produce offspring like Esav (the grandfather of Amalek). In a nutshell, these offspring are the klippah, which is why Yaakov Avinu is considered the pinnacle of spiritual shlaimut (wholeness) and the sefirah of Tiferet -- because he produced no klippah in his offspring. (Though they weren't perfect because no one is perfect except Hashem, but they certainly possessed exalted Jewish souls.)
But the point is that finding a Jewish ancestor in the bloodline of a despicable person -- including a Jew-hating person -- is nothing new and probably shouldn't spark neither undue interest nor undue shame.
It's a klippah going way, way back.
But we can learn from both ancient history and more recent history that it's best to make good decisions (like Yaakov Avinu) and avoid intermarriage and then, based on the above, I suppose you'll then avoid producing this kind of klippah.
May we all merit receiving Mashiach Tzidkeinu sweetly in our times.