Nootbaar has a multi-ethnic background, as he belongs to the Dutch-Japanese ethnicity. His parents come from different ethnic backgrounds; his father is Dutch, while his mother is Japanese. 

Lars’s parents met when they were college students at Cal Poly San Luis Obispo; his mother was a foreign exchange student. Later she moved back to Japan, and his father also traveled to Japan to continue his studies.

When he reached Japan, the host family dropped out at the last moment. He called the only person he knew in Japan his now wife. Due to the situation, they re-united and are still together to date.

Lars believes that most of his ethnicity comes from his mother’s side; he has added Tatsuji in his middle name for his mother.