John Francis Pastorius III was born December 1, 1951 in Norristown, Pennsylvania to John Francis Pastorius II and Stephanie Katherine Haapala Pastorius, the first of their three children. Pastorius was of Finnish, German, Swedish, and Irish ancestry.
Shortly after his birth, his family moved to Fort Lauderdale. Pastorius went to elementary and middle school at St. Clement's Catholic School in Wilton Manors, and he was an altar boy at the adjoining church. In his years at St. Clement's, the art he was most known for was drawing.
Pastorius formed his first band named The Sonics along with John Caputo and Dean Noel. He went to high school at Northeast High in Oakland Park. He was a talented athlete with skills in football, basketball, and baseball, and he picked up music at an early age. He took the name "Anthony" at his confirmation.
He loved basketball, and often watched basketball with his father. Pastorius' nickname was influenced by his love of sports and also by the umpire Jocko Conlan. He changed the spelling from "Jocko" to "Jaco" after the pianist Alex Darqui sent him a note. Darqui, who was French, assumed the name was spelled "Jaco"; Pastorius liked the new spelling. Jaco had a second nickname, given to him by his younger brother Gregory: "Mowgli," after the wild young boy in Rudyard Kipling's classic The Jungle Book. Gregory gave him the nickname in reference to Jaco's seemingly endless energy as a child. Jaco would later establish his music publishing company as Mowgli Music. http://en.wikipedia.org/wiki/Jaco_Pastorius