Frentzen was born on 18 May 1967 in the West German city of Mönchengladbach (North Rhine-Westphalia) to Heinrich-Harald Frentzen, a German entrepreneur and his Spanish wife Angela Lladosa. He has two sisters (Sylvia, a theologian, Sonja, a teacher) and two half-sisters (Samantha, a former student, and Nicole-Nadine). His family was connected to motorsport; his father raced between 1950 and 1957. Frentzen's parents divorced when he was eight years old and his father subsequently married Mexican-born Arazelli while Angela returned to Spain.