Kern is the daughter of the German biochemist and former national basketball player Dorothee Kern , who went to the United States in the 1990s.
She started in January 2013 in Midway for the first time in the US Super Tour and finished 34th in the sprint. At the Nordic Junior World Ski Championships in 2015 in Almaty , she took 38th place in the skiathlon , 32nd place in the sprint and eighth place in the relay. In the 2015/16 season she reached 20th place overall at the US Super Tour. She came on the podium for the first time in Craftsbury in February 2016 with second place over 10 km. At the Nordic Junior World Ski Championships in 2016 in Râşnov , she took 18th place over 5 km classic, 16th place in the sprint and eighth place with the relay. At the beginning of the 2016/17 season, she won the sprint at the Nor-Am-Cup and US Supertour races in Vernon . In the further course of the season she took her first victory in the US Super Tour in the sprint in Ishpeming and took third place in the sprint at the US Super Tour in Auburn . At the Nordic Junior World Ski Championships 2017 in Soldier Hollow , she won the bronze medal with the relay. In addition, she was ninth in the sprint there. In March 2017, she made her debut in Quebec in the cross-country skiing world cup . There she got her first World Cup points in the World Cup final , which she finished in 46th place, in the sprint stage with 24th place.
In the 2018/19 season, Kern took three wins in the US Super Tour. In addition, she took third place three times and second place once and thus won the overall ranking. At the World Cup finals in Québec she came in 43rd place and with three places in the points she reached 73rd place in the overall World Cup. At the season highlight, the Nordic World Ski Championships 2019 in Seefeld in Tirol , she finished 23rd in the sprint, 19th in the skiathlon and fifth in the relay. The following season she finished 49th in the Ruka Triple and 30th in the ski tour. She also achieved her first podium finish in the World Cup with third place in the sprint in Planica and at the end of the season she finished 40th in the overall World Cup and 19th in the Sprint World Cup. At the U23 World Championships 2020 in Oberwiesenthal , she won the bronze medal in the sprint. In addition, she ran there on the 27th place in the 15 km mass start race, on the fifth place with the relay and on the fourth place over 10 km classic.