Anna was treated by her creator, Dr. Keffler, more as a science experiment than a human being, and was never allowed outside of the secret facility in Los Angeles where she was created and held prisoner in a clear box. Keffler gave her many books describing the world outside, but she never saw the sun. He gave her sketch pads and drawing utensils to depict the dark images within her mind, which came from the Goa'uld Sekhmet's remnant genetic memories. Once Keffler told her it was for her birthday, likely meaning she was less than two years old, despite her appearance as a fully-grown woman.
Keffler's prime commitment was to use Anna's darker side to discover secrets of the Goa'uld, ultimately to save mankind. He tortured her to cause the latent Goa'uld personality come out. At the base of Anna's brain was implanted a supply of biotoxin that, when detonated with Keffler's hand-held device, would cause a humane death within moments.
Sekhmet ultimately offered her captor nothing of value. Anna herself was continually plagued by black-outs, her innocent nature only able to interpret the evil within her by creating horrific drawings. She eventually escaped under the influence of Sekhmet, who killed the scientists -- all except Keffler -- and set a Goa'uld bomb before being recaptured. SG-1 soon arrived with Malcolm Barrett -- an agent of the legitimate N.I.D. organization -- and Daniel Jackson became a close confidant to Anna and tried to get her to focus the memories she possessed. When Sekhmet appeared she used the candle in her cell to set Anna's drawings on fire, and eventually escaped.
At this point Anna regained control (though she may have been in control much of the time) and killed Dr. Keffler. She realized there was nothing that could be done to save her, and she used his device to release the biotoxin, killing herself.
Resurrection - Agent Barrett asks Dr. Jackson to attempt to break the ice with Anna, a Goa'uld-human hybrid who has been tortured for an untold amount of time for information hidden within her mind.