Trivia: The appearance of Charles Lee Ray on-screen during the flashback sequences marks the first time that Brad Dourif had appeared in human form in one of the "Chucky" films since the original. (Although photos of him from the original did subsequently appear in the other sequels, he had not shot any new live-action material in 25 years).
Trivia: The production attempted to keep the cameo performances of Jennifer Tilly and Alex Vincent secret. They were unlisted in the cast and promotional material for the film. However, after early screenings of the film, their cameos were leaked online.
Trivia: Spoilers. When Tiffany appears in a bit of a surprise cameo, her introduction is an almost shot-for-shot recreation of her introduction two films prior in "Bride of Chucky." Even the circumstances are the same - Chucky is in a black garbage bag having been taken from evidence by a cop who is selling her to Tiffany.
Trivia: Had the longest timegap between sequels, coming out nine years after the previous film, "Seed of Chucky." The long wait was in part because a few years after "Seed" was released, several attempts were made to remake/reboot the series, given the rising popularity of 80's slasher-film reboots. Despite several false starts, the reboot never happened. Eventually, series creator Don Mancini opted to instead perform a "tonal reboot" of the series with this film - by setting it in the same "universe" as the other movies, but shifting the focus back to classic horror and delivering a film more tonally similar to the original 1988 film. Mancini wanted to please fans, who expressed interest in seeing another "scary" Chucky movie after the previous two films had become increasingly comedic in tone.
Trivia: Several of the exterior shots of the house are either entirely CG or have CG elements added to them. For example, the overhead shot of the delivery truck pulling up to the house was entirely digital. And some digital greenery was added to live-action shots of the real house to make it seem more secluded. Due to the low budget nature of the film, it was easier (and cheaper) to use simple digital effects than to rent helicopters for overhead shots and add in fake trees and plants.
Answer: The films don't delve into either Chucky or Tiffany's backstory, and the films themselves are the only official canon. So until it is properly addressed in the movies, it's basically up to your imagination.