You obviously haven't lived in a totalitarian country. My girlfriend is from a Soviet-Era-communist country. She was very young when the communist regime was repelled but she has distinctive memories of the era, how you could only get state television channel, how going abroad was almost impossible, how it was impossible to get foreign made goods, how the country was everything and criticizing the country was frowned upon.
In addition, please remember that Antisemitism in Soviet Union was a de-jure policy after WW2. Also remember, that Sergey Brin's parents were academics, which made them an active target of the government.
If you live not under a fear of the government but also under the fear of a government openly hostile to your community and your parents are marked people, it makes a pretty damn good impact on your childhood. In addition, do you think as a child his parents would've never talked about their life in Soviet Union ? These are the experiences that shape your thinking.
Just because he was young doesn't mean he doesn't know how it was.