Generally speaking Lilli Beckham and her older sister Jade grew up in a very normal environment. They have a loving mother named Ruth and a hard working father named Joseph. Their father although he loves his daughters very much, pushed them very hard. If one of the girls had anything lower than a 4.0 GPA they would be grounded and any toys and electronics would be taken away. They were expected to stay in Tae Kwon Do until they turned at least 18 because, he felt he wouldn't always be there to protect them in their home city, Gotham, which has a very high crime rate and danger level.
Lilli was forced into swimming since a young age and she continued to excel at it through high school. Lilli was a great student and athlete. Her boyfriend during high school, Parker, was very controlling but seeing as she "loved" him she couldn't recognize the problems. Meanwhile Jade began a downhill spiral into smoking and finding herself in jail a few times, so when Jade pointed out Lilli's relationship problems, Lilli began to resent her sister. Her friends slowly stopped hanging out with her as well. Senior year Parker slapped Lilli across the face because, she had accused him of cheating on her with the school slut. Which she later found out was true. This was when she finally realized his abusive nature. She used her eleven years of Tae Kwon Do experience and kicked the shit out of him.
Although Lilli quickly moved on trying not to dwell in the past. She ended up going to college at the age of 18 in Gotham. She was accepted at other places she couldn't bring herself to leave her parents. She studied at this college until she was 22 earning multiple degrees in Biology, Medicine, and Chemistry. Graduating at the top of her class.
Jade at 23, had turned around her life. She's COO [Chief Operating Officer, a position that is right below CEO] of Wayne Enterprises. Lilli and Jade had made up with after a long crying session and lots of apologies between them. Lilli immediately got a job at Wayne Enterprises because of her sister's status. Lilli is now one of the leading minds in the Wayne Biotech Branch. Lilli now at age 24 wanting to get some space between her and her parents, decided to move in with her 25 year old sister who currently resides in Central City. Just in time for the particle accelerator explosion.