More information on Lenin's partial Jewish ancestry 
The following quotes regarding Lenin's partial Jewish ancestry are from The Jewish Century by Yuri Slezkine (Princeton University Press, 2004) and could possibly be inserted in to this article in order to provide more references.

 "But of course the most sensitive "nationality" [ethnicity] of all was Lenin's. In 1924, Lenin's sister Anna discovered that their maternal grandfather, Aleksandr Dmitrievich Blank, had been born Srul (Israel), the son of Moshko Itskovich Blank, in the shtetl Starokonstantinov [Old Konstantinov] in Volynia [Volhynia, now Ukraine]. When Kamenev found out, he said, "I've always thought so," to which Bukharin allegedly replied: "Who cares what you think? The question is, what are we going to do?" What "they," or rather, the Party through the Lenin Institute, did was proclaim this fact "inappropriate for publication" and decree that it be "kept secret." In 1932 and again in 1934, Anna Ilinichna [Lenin's sister] begged Stalin to reconsider, claiming that her discovery was, on the one hand, an important scientific confirmation of the "exceptional ability of the Semitic tribe" and "the extraordinarily beneficial influence of its blood on the offspring of mixed marriages"; and, on the other, a potent weapon against anti-Semitism "owing to the prestige and love that [Vladimir] Ilich [Lenin] enjoys among the masses." Lenin's own Jewishness, she argued, was the best proof of the accuracy of his view that the Jewish nation possessed a peculiar "'tenacity' in struggle" and a highly revolutionary disposition. "Generally speaking," she concluded, "I do not understand what reasons we, as Communists, may have for concealing this fact. Logically, this does not follow from the recognition of the full equality of all nationalities." Stalin's response was an order to "keep absolutely quiet." Anna Ilinichna did. The enemies of the regime were deprived of additional anti-Semitic ammunition" (pgs. 245–246)

 "All advanced Jews supported assimilation, according to Lenin, but it is also true that many of the "great leaders of democracy and socialism" came from "the best representatives of the Jewish world." Lenin himself did [have Jewish ancestry], through his maternal grandfather, although he probably did not know it. When his sister, Anna, found out, she wrote to Stalin that she was not surprised, and "this fact" was "another proof of the exceptional ability of the Semitic tribe," and that Lenin had always contrasted "what he called its 'tenacity' in struggle with the more sluggish and lackadaisical Russian character." (p. 163)

 "And in 1965, all archival documents relating to Lenin's Jewish grandfather were ordered "removed without leaving any copies." (pg. 338)