Janez Lampic was born on 27 September, 1996 just after his elder sister's birth in 1995. His father, Janez Lampič was a professional road cyclist who represented Yugoslavia at the 1984 Summer Olympics and competed in the men's team time trial event. His elder sister, Anamarija Lampič is also a cross-country skier who has competed at the World Championships held in 2015 and 2017 before earning an opportunity to compete for Slovenia at the 2018 Winter Olympics. Coincidentally, both Janez Lampič and Anamarija Lampič made their Olympic debuts during the 2018 Winter Olympics and competed in the cross-country skiing events.