Across the world, Костькин (Костькин ) is an extremely rare unknown gender first name. Much more frequently, Костькин is the last name as well as the forename.
Kostkin
Петр, Александр, Владимир, Григорий, Геннадий, Анатолий, Евгений, Василий, Валерий, Николай, Дмитрий, Владислав, Алексей, Сергей, Виктор, Никита, Андрей, Михаил, Роман, Павел, Юрий, Иван, Илья, Сергий, and Константин
) is an extremely rare unknown gender first name. Much more frequently, Костькин is the last name as well as the forename.