A non-negligible percentage of corresponding members of Academy of Sciences of the USSR were born in rural areas [1] (look at these who were appointed at around 1970-1980, they most probably born in USSR).

[1] https://ru.wikipedia.org/wiki/%D0%A1%D0%BF%D0%B8%D1%81%D0%BE... (Russian)

How do they come to such heights if applying to the study in large cities was restricted, is a complete mistery to me.