Kärt was born in 1764. Kärt's father was Toots and her mother was Liis. Her paternal grandfather was Peeter and her paternal grandmother is <Unknown>; her maternal grandparents were Jaan and Els. She had a brother and four sisters, named Tõnn, Liis, Tiiu, Mai and Ann. She had four half-brothers and five half-sisters, named Toomas, Paap, Peep, Mikk, Katri, Kärt, Annika, Mai and Katri.