Born in Costa Rica, Jenaro began playing the violin at age seven in the Youth Program of the National Symphony Orchestra of Costa Rica.

By the age of thirteen, Jenaro began his viola studies and quickly advanced, becoming a full-time member of the Costa Rican Orchestra's viola section just two years later.

At seventeen, Jenaro received a scholarship from the Israeli government to study at the Music Academy at Tel Aviv University. He continued to excel and, at twenty-one, secured a full scholarship to Indiana University, Bloomington, where he spent an additional two years refining his skills.

In 1991, Jenaro relocated to New Zealand and became a member of the Auckland Philharmonia before joining the New Zealand Symphony Orchestra's viola section in 1994.