I wonder why some Slavic surnames change with gender, while others do not.
Russian: The surname of Lev Tolstoy's wife and daughters was Tolstaya. We see dozens of examples of Russian surnames in Tolstoy's novels, such as Anna Karenina, the wife of a government official named Karenin, and Natasha Rostova, daughter of Count Rostov.
Polish: Władysław Skłodowski, a Polish secondary-school teacher, was the father of Maria Skłodowska, later Marie Skłodowska-Curie.
Ukrainian: The most common Ukrainian surnames end in either -uk or -enko, but those endings don't change with gender. Why not? Does anyone here know?

