Even in Louisiana, "very few people have heard of Judah Benjamin, unless they are Jewish or Civil War buffs," said Laura Cassidy, a fifth-generation descendant of Benjamin through his sister, Rebecca Benjamin Levy. (Emphasis added.)
(Jonathan Tilove, Resurrection: Groundbreaking Statesmen Judah Benjamin is All But Forgotten Today, But a New Exhibit Could Change That, Times-Picayune, April 20, 2010, at A1.)
Yeechhh!!! She's descended from Benjamin and an incestuous union with his sister? Very, very, sloppy, poor choice of woods. Yeah, obviously she's not a "descendant" of Benjamin, but of her sister. Maybe a "descendant of Benjamin's family through his sister..." or, even better, "her great-great grandmother was Benjamin's sister, Rebecca Benjamin Levy". But not descended "through his sister". Sounds like another sequel to Mandingo.