 Castel was born in Lisbon, Portugal, the "scion of a multigenerational dynasty of Sephardic rabbis" with roots in 15th century Castile.He was raised in Venezuela by multilingual parents and a German nanny and attended a French school in Caracas.After some vocal study in Caracas and then the University of Mainz in Germany, Castel moved to New York City at the age of 16 to pursue a singing career and to study romance languages at Temple University in Philadelphia.