I think he does have siblings
Sofia Kovalevskaya had two siblings: an older sister named Anna and a younger brother named Sergey. Anna was also known for her intellectual pursuits, while Sergey became a military officer. The family's supportive environment fostered Sofia's early interest in mathematics and science, contributing to her groundbreaking achievements in those fields.
Sergey Twob's birth name is Sergey Sergeevich.
Sergey Shnyryov's birth name is Sergey Yurevich Shnyryov.
Sergey Strelnikov's birth name is Sergey Aleksandrovich Strelnikov.
Sergey Tsyss's birth name is Sergey Svetlanovich Tsyss.
Sergey Reshetnikov's birth name is Sergey Nikolaevich Reshetnikov.
Sergey Alimov's birth name is Sergey Aleksandrovich Alimov.
Sergey Bezrukov's birth name is Sergey Vitalevich Bezrukov.
Sergey Bachurskiy's birth name is Sergey Konstantinovich Bachurskiy.
Sergey Bodrov's birth name is Sergey Vladimirovich Bodrov.
Sergey Brin's birth name is Sergey Mikhailovich Brin.
Sergey Artimovich's birth name is Sergey Mikhaylovich Artimovich.