Young has more than a dozen arrests for mostly minor marijuana possession charges that were later dropped. His only conviction appears to be a misdemeanor criminal trespass to a vehicle; he was sentenced to four days he had already served in jail.
Young's brother, Devon, was fatally shot by Chicago police in June 2008, according to his family and records.
Jett was arrested in March 2010 on a felony drug possession charge and then while out on bond picked up a crack-cocaine possession charge the following October, records show. He pleaded guilty to both charges and was sentenced to 24 months probation. Last September he was arrested on a probation violation and jailed until November.
Gatewood, who has no criminal background, is currently enrolled as a culinary student at Kennedy-King College, the school confirmed.
The arrest stunned his mother, who held back tears during an interview Tuesday outside her home.
"Half of me is gone," said Jacqueline Irvin, who indicated her son has been cooking the family Thanksgiving and Christmas dinners since elementary school.
She said Gatewood was home with her Thursday night playing video games. The two had talked briefly Tuesday, she said.
"(He's) very scared because it's something new for him," she said.
Tribune reporters Rosemary Regina Sobol, Carlos Sadovi, Liam Ford, Steve Schmadeke and Lauren Zumbach contributed.