Sergei's mother, Ludmila Vsevolodovna Keldysh, was also an outstanding mathematician who became a professor of mathematics and made important contributions to set theory and geometric topology .
Daisy's ina, Ludmila Vsevolodovna Keldysh, ay din ng isang natitirang dalubbilang na naging isang propesor ng matematika at ginawa mahalagang kontribusyon upang magtakda ng teorya at geometriko topology.