Not much is known about Julia's life before coming to G889. We are not even sure about her birthday. But surmising she was about 25 years old at the time of the crash (not counting cold sleep, of course), we can guess she was born around 2167.
We do know something about her mother and her youth though. Councilwoman Heller was dedicated to the Council, the unofficial but actual government, and was a member of the board of regents. She lived her life for her work and had little time to spend on her daughter's upbringing, let alone her emotional welfare.
Julia has been 'genetically enhanced' to discourage emotional reactions and been skewed towards medicine, which makes her such a smart and efficient doctor, but so poorly equipped to handle emotional issues.

Despite her young age, Julia Heller was an apprentice with Dr. Vasquez, the Station's expert on the disease called the Syndrom which only afflicted young children, none who lived past the age of 9. Both doctors were supposed to be on the advance ship heading for G889, where they hoped to find a cure for the disease. Due to the unscheduled early departure of the ship, Julia found herself suddenly being the only doctor aboard and thus she became the resident expert on all medical things.

When the Council found out Julia Heller was going to go to G889 with the Eden project, they immediately enlisted her help, calling on the loyalties ingrained in her from before her birth.
The Council had been interested in the planet for years, had even sent a Council representative to the planet, but had not made much progress in the colonization of the place. Having someone on planet that would not only be loyal to the Council's plans but was also capable of studying the medical and metaphysical aspects of the planet sounded almost too good to be true. Julia couldn't resist the call on her loyalties and agreed to keep the Council informed.

When the advance ship crashed on the planet, the small group of survivors was at a loss. Thousands of miles from their destination, without the necessary supplies, they needed their doctor's expert knowledge. Depending upon each other for their survival, the small group quickly became a close knit family-like entity, despite their different backgrounds. Julia reluctantly contacted her Council contact, but never trusted him enough to give him her location.
She was torn between the voices of reason and heart, as she felt herself become closer to the group and especially her first patient, the advance ship's pilot, who suffered a broken leg during the crash. Not knowing which of her loyalties to adhere to -to the Council or to her new found family- she became very confused and drew back on her only defense: professionalism.

When requested to perform a secretive and very dangerous operation on a little boy, Julia rebelled. The operation went against her ethics and the native Terrians warned her it would kill the boy. Instead, she volunteered to experiment on herself, trying to divert the Council from the Eden crew. The experiment went horribly wrong, and the group left her behind. Full of remorse about leaving her, the pilot returned to bring her back. The rest of the Advance crew, though in doubt about their rash decision to leave her, were not so quick to forgive the doctor. But when she redeemed herself by taking on a ZED, a Council super soldier, they took her back in, believing as humans they should give her a second chance.

Thus she became the trusted and valued friend of the first of the Eden colonists. Julia Heller and her family are currently residing on G889.