https://en.wikipedia.org/wiki/Lev_Landau

In 1937 Landau married a girl from Kharkov, Kora T. Drobanzeva;[9] their son Igor was born in 1946. Landau believed in free love rather than monogamy, and encouraged his wife and his students to practice free love; his wife was not enthusiastic.[5]

>>9
Article doesn't provide a proof she is gentile.

then she could pass for a 1/2 Jewess

compare a well known Jewish rights defender Lyudmila Alexeyeva (her real name is Slavinsky)
http://commons.wikimedia.org/wiki/File:Lyudmila_Alexeyeva_2011-03-10.jpg

to le Guin:
http://farm4.static.flickr.com/3576/3502029626_1638eb2205_o.jpg