Libby is a 33yo British transplant that moved to Boston at age 14 with her adoptive parents and adoptive brother. Formerly an international supermodel who was discovered at a young age, but she has retired from that at the end of September 2016. Since then she's started in the MSW program at BU. Maybe her family could have fostered her for a while until Libby's adoptive parents died in an accident while Libby was in college. If you go with astrophysicist, it could have been partially influenced by Libby's father and brother who were both academically trained as physicists?