http://content.time.com/time/world/article/0,8599,2077413,00.html

The declassification of documents since the collapse of the Soviet Communist tyranny in 1991 has brought irrefutable proof that Lenin’s maternal great-grandfather was a shtetl Jew named Moshko Blank. Whether or not Lenin himself was aware of this piece of information is uncertain, but by the time of his death in 1924 his sister had possession of the facts—and, by order of the Central Committee of the Communist party, was forced to keep them secret. The order held firm until the dissolution of the Soviet Union in the early 1990’s.