After her mother's death, Athina was raised by her French father Thierry Roussel, who later married Gaby Landhage from Sweden. As Athina's step-mother, Gaby provided a stable and protective family environment for Athina in the family's five-bedroom villa in Lussy-sur-Morges, Switzerland.
On her 18th birthday, Athina inherited an estimated US$2.7 billion worth of cash, property, jewels, and other assets from the Onassis estate. On her 21st birthday, she will become the president of the Onassis Foundation, with assets in excess of US$2.1 billion.