László was born on February 3rd, 1921 in Eger. László's father was Sándor Körtvélyesi and his mother was Mária László. His paternal grandparents were János Körtvélyesi and Mária Gajdácsik. He had two sisters named Mária and Erzsébet. He was the second oldest of the three children. He died at the age of 74 on October 29th, 1995.