János was born in 1914. János' father was Pál Körtvélyessy and his mother was Mária Kalló. His paternal grandparents were János Körtvélyessy and Borbála Kruppa. He had two brothers and a sister, named Pál, László and Mária. He was the youngest of the four children. He died at the age of 78 in 1992.