Körtvélyessy was born in 1944. Körtvélyessy's father was Dr Dezső Körtvélyessy and his mother was Teréz Sárossy. His paternal grandparents were Károly Körtvélyessy and Jolán Vecsery. He had a brother and a sister, named András and Zsuzsa. He was the oldest of the three children. He died at the age of 4 in 1948.