Parker's family has lived on Chicago's South Side since before Jabari was born, and he was raised in the South Shore community area. Parker's father, Sonny, has served hundreds of Chicago metropolitan area children as youth foundation director since 1990. Parker discovered basketball in one of his father's many leagues, although his father has never coached one of his teams. He honed his basketball skills with his brother Christian on the basketball court at his local Church of Jesus Christ of Latter-day Saints meetinghouse in the Hyde Park community area in order to avoid the hazards of urban playgrounds. By second grade his basketball skills were superior to those of the fifth-graders he played with, and he competed in middle school leagues as a fifth grader. He credits his cousin Jay Parker for pushing him to be better, starting when Jabari was in third grade and Jay was in fifth. Sometimes, Jabari and Christian played basketball all through the night at the church. Jabari actually made the eighth-grade team as a fourth-grader, but could not play until fifth grade for insurance reasons. In fifth grade, he had five Division I scholarship offers as a 6-foot (1. 83 m) guard. In sixth grade, when he stood at 6 feet 2 inches (1. 88 m), he visited Simeon for a day and scrimmaged with Derrick Rose. Parker attended Robert A. Black Magnet Elementary and made headlines when he made Simeon Career Academy his high school choice, just like Rose, Nick Anderson, Ben Wilson, Bobby Simmons and Deon Thomas before him. Parker has two older sisters who had attended Simeon. However, he has claimed that the reason he chose Simeon was due to his perception of the likelihood that he could achieve team success on the basketball court (as measured in championships). During the summer after finishing middle school, he received a National Basketball Players Association Top 100 Camp invitation, which he accepted. By this time, he stood at 6 feet 4 inches (1. 93 m).