Olivia also mentioned having attended a boarding school, but this was in "Safe" and may have been part of John Scott's memory instead.
There's no real information on any of this. There are possibilities:
* Her father was reassigned between the time she was 3 and 8, until he died or divorced her mother, after which her mother returned to Jacksonville;
* The Cortexiphan trials ended in 1983, and the family moved elsewhere. Walter used his Defense Department contacts to have some of the Cortexiphan subjects returned to Jacksonville in 1985/86 to work on the crossing capability;
* Her mother lost custody of her and her sister after the shooting incident, and her father? uncle? other guardian? was in the military and was stationed in several places while she was in her teens. This would likely tie in with the boarding school if the guardian were stationed abroad for a period of time.
This is all guesswork since there's no dialog to support any of it.
As for Olivia's memory, we have Nick Lane in "Bad Dreams" indicating that "they" (read, Bell & Bishop) intended the children to forget about the trials. Many people have assumed this means some sort of treatment was given the children to make them forget.