Trivia: Co-star Danielle Bisutti was related to a studio executive at United Artists. When she was a kid, she visited the studio and saw the poster for the original "Child's Play" and was horrified by it, saying that it "haunted" her. This makes it all the more ironic that she would go on to star in "Curse of Chucky," one of its many sequels.
Trivia: Christine Elise, who previously played Kyle in "Child's Play 2", was originally meant to play Nica's mother in a cameo, as director Don Mancini wanted to work with her, but due to casting laws in Canada, where the film was shot, Elise wasn't able to be cast. Mancini later brought her back as her original character Kyle in "Cult of Chucky" and the "Chucky" TV series.
Trivia: Lead effects artist Tony Gardner actually filmed Chucky's voice actor, Brad Dourif, when he was recording his lines to use as reference, since Dourif had a tendency to move and gesture a lot when recording his lines. Gardner then had the puppeteers replicate Dourif's mannerisms as closely as they could with the Chucky doll. Dourif's daughter, Fiona, who stars in the film, was very amused by the fact Chucky was moving almost exactly like her father does in real life.
Trivia: The elevator seen throughout the movie wasn't actually properly functional, since building a functional elevator would have been prohibitively expensive. In order to make it move, it was rigged to a forklift via a concealed winch. The forklift would drive back and forth, pulling the winch and making the elevator move up and down.
Trivia: The interior of the house is actually the same indoor set used for the 2012 TV movie "Home Alone: The Holiday Heist." Since it was already built, it saved the production a ton of money. All they had to do was modify it to look more gothic and add the elevator, and it suddenly looked like a completely different "house."
Trivia: In the first cut of the film, Alice was actually killed by Chucky right after he comes to life, and she would have been the first victim, as well as Chucky's youngest victim at that point in the franchise. However, due to the tragic Sandy Hook shooting, the studio and director Don Mancini decided to change her fate and instead have Chucky possess her. The scene of Chucky locking her in the closet and the final scene of her being possessed were added during post-production.
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.