The Walford favourite, who was cast as a teenager when the show started in 1985, makes a dramatic return in tonight's episode.
She told the Radio Times: "I did tell a little white lie. The show's creators Julia Smith and Tony Holland wanted real Cockneys, people who'd been born within the sound of Bow Bells.
"And I told a porkie - I think I said my parents were abroad and that I was staying with an auntie in Hackney. So it was all, 'Awight Julia. Nice to meet you, gel'."
The 44-year-old also praised new executive producer Lorraine Newman for her new "insight" into Sharon's character.
Dean has previously admitted that she is "nervous" about watching her on-screen Albert Square comeback.