Mstislav Keldysh

Keldysh was born to a professional family of Russian nobility. His grandfather, Mikhail Fomich Keldysh (1839–1920), was a military physician, who retired with the military rank of General. Keldysh's grandmother, Natalia Keldysh (née Brusilova), was a cousin of general Aleksei Brusilov. Keldysh's maternal grandfather, Alexander Nikolayevich Skvortsov, was a General of Infantry, and fought in the Caucasian War.

Keldysh's father, Vsevolod Mikhailovich Keldysh (1878–1965), was a civil engineer, Major General of the Engineering Service, and a full professor, teaching at the Kuybyshev Military Engineering Academy from 1918. He became a Distinguished Engineering Scientist of the Soviet Union (Заслуженный деятель науки и техники СССР) in 1944. He was one of the authors of contemporary methods for calculating the strength of reinforced concrete, and a designer of the Moscow Canal and Moscow Metro projects.

Several members of the Keldysh family were victims of political repressions. In the 1930s Keldysh's uncle was sent to a labor camp on the White Sea–Baltic Canal construction site. In 1935 Keldysh's mother was arrested but was released after a few weeks. It was a part of the campaign of collecting gold from the population, but after Keldysh's father brought all the jewelry the family had, the unsatisfied NKVD officer returned "all this garbage" back. Keldysh's brother Mikhail, a historian who specialized in Medieval Germany, was arrested in 1936 and executed in 1937 on suspicion of being a German spy. In 1938 another of Keldysh's brothers, Alexander, was arrested as a French spy. Alexander was spared because of the slight liberalization of the repressions during the transfer of the NKVD leadership from Nikolai Yezhov to Lavrentiy Beria, and was acquitted in the court.

The strongest influence on Keldysh was his older sister, Lyudmila Keldysh (1904–1976), a mathematician and Keldysh's first teacher. Among her children are Leonid Keldysh, director of Lebedev Physical Institute and Sergei Novikov, a mathematician.