Many people got to it first, but Jorge dies in an explosion in space, in the mission "The Package", that is Jun who goes with Dr. Halsey. His fate is unknown.
It just occurred to me that they might reveal Jun's fate in HALO 4........
Also, Dr. Halsey isn't his mom, she is just a mother figure to him. In her lab notes that came in the legendary edition that I got it says she personally attended to him since he was a child. She is in a sense his mother, but not genetically.