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 Bezrukov's birth name is Sergey Vitalevich Bezrukov.
Sergey Petreykov's birth name is Sergey Dmitrievich Petreykov.
Sergey Polezhaev's birth name is Sergey Aleksandrovitch Polezhaev.
Sergey Olifirenko's birth name is Sergey Alekseevich Olifirenko.
Sergey Reshetnikov's birth name is Sergey Nikolaevich Reshetnikov.
Sergey Shnyryov's birth name is Sergey Yurevich Shnyryov.
Sergey Tsyss's birth name is Sergey Svetlanovich Tsyss.
Sergey Strelnikov's birth name is Sergey Aleksandrovich Strelnikov.
Sergey Kositsyn's birth name is Sergey Petrovich Kositsyn.
Sergey Kuchkov's birth name is Sergey Fyodorovich Kuchkov.