The names for the oldest two girls, Olga and Tatiana, seem to be from Pushkin's "Eugene Onegin" written in the 1800's, although there may be other reasons for them as well.
In case you're interested, here's a short summary as to what it's about:
Evgenii Onegin is a dashing young aristocrat : "In French Onegin had perfected / proficiency to speak and write, / in the mazurka he was light; / his bow was wholle unaffected." On inheriting his uncle's estate, he retires to country. Soon Onegin befriends Vladimir Lenskii, who is in love with a local girl, Olga Larina. Her unpolished, romantic elder sister Tatiana falls in love with Onegin, but he rejects Tatiana's love. He considers himself mysteriously doomed, he would be a bad husband. "But I for bliss was not created: / To that my soul is foreign still. / In vain, in vain, are your perfections;/ Of them I count myself unworthy." At a party Onegin insults Olga, and Lenskii challenges him to a duel, and is shot dead. Three years later Onegin meets Tatiana who is married to a prince. He declares his love to her, and writes her a series of letters expressing a mad passion. Now it is her turn to reject him. She confesses that she loves him but insists that they must part for good. Pushkin's novel has been a rich source of character types for Russian writers. Tatiana has been regarded as the ideal of Russian womanhood. She is faithful, generous, sincere, and considerate.
