Unfortunately when Nico was a kid he had a cancerous tumor on his neck and cheek.
Because of the chemo and radiation treatments to get rid of the tumor, his vocal cords were damaged, which resulted in Nico having a high pitched voice as an adult.
The treatment also messed with the growth of his teeth.
They made his bottom teeth very weak, and they fell out pretty easily as a teen. Later in his early 20’s dentists decided to remove all of his bottom teeth.
Nico was so insecure about his voice and teeth that he rarely approached women at bars or anywhere outdoors, and became addicted to online dating - which really limited his dating opportunities.