Pajaro's parents were immigrants from Colombia living in New York City. His father was an accomplished musician and songwriter and young Octavio excelled at piano from a young age. Though his music instructors encouraged him to enroll at Juilliard, he applied to Harvard, instead, to pursue his love of math and science.
While studying biochemistry, Pajaro met fellow student and vocalist Dominique van der Stadt, whom he later married. He pursued his medical degree at the Albert Einstein School of Medicine (1990), and interned at Johns Hopkins Medical Center in Baltimore, Maryland until 1996. He completed a Fulbright fellowship at Oxford University and worked from the Mayo Clinic's Jacksonville, Florida campus before coming to UAB in 2007.
Pajaro continues to play piano and the couple's four children, Milena, Adrian, Flavia and Stefan are all musically inclined.
- Huebner, Michael (August 15, 2010) "Old City String Quartet member comes from Mountain Brook home filled with music." Birmingham News