Casey,
the article didn't mention Joan Didion, which prompted me to wonder how exactly is she a descendant of a Donner Party member. Per a 1979 New York Times profile,
https://www.nytimes.com/1979/06/10/books/didion-calif.html
Didion descended from a member of the luckier half of the group, which took the northern route, thus missing out on the Donner buffet:
"Joan's great-great-great-grandmother, Nancy Hardin Cornwall, was a member of the original Donner party, but she had left the ill-fated group at Humboldt Sink in Nevada to cut north through Oregon."
Dan