The very first episode of Netflix's Jessica Jones begins with a slice of Jessica Jones' (Krysten Ritter) daily life. She's a P.I. who uses her super-human abilities to help her track people down – typically cheating spouses — for a quick payout. Season 1 of Jessica Jones never hides that Jessica has superpowers, but never elucidates how she got them. That changes in season 2.
In the comic books, Jessica Jones' powers are bundled up with tragedy. When Jessica is 16, her father gets tickets for the family to visit Disney World through his job at Stark Industries (yes, Tony Stark's company). The trip to Orlando proves fatal.
After crashing into a military convoy carrying radioactive materials, Jessica's father, mother, and brother die, and Jessica falls into a months-long coma. When she wakes up, she discovers that exposure to radioactive chemicals has given her powers of strength and flight. She's adopted by the Jones family (not Patsy Walker's family), and changes her last name from Campbell to Jones. Jessica keeps her powers a secret until she witnesses Spider-Man in action and is inspired to actually put her abilities to use. In the period of her life before meeting Kilgrave, Jessica worked as a superhero with the codename Jewel.
The Netflix show differs slightly from the comic book source material, so the way Jessica gets her powers is different, too. In the show, the crash comes as a result of Jessica arguing with her brother. Unlike in the comics, the truck the car crashes into isn't carrying hazardous materials; it's just a normal truck. Then, Jessica is adopted by Patsy Walker's mother, not the Jones family.
The trailer for Season 2 indicates how Jessica may have gotten her powers: A shady company called IGH, which funneled patients from hospitals to their own genetic experimentation labs, and gives people powers. IGH is mentioned at the tail end of the first season, when William Simpson (Wil Traval) obtains super-charged medication from Dr. Kozlov (Thomas Kopache), a doctor who works for IGH. These pills turn Simpson into a fighting (and killing) machine. Clearly, IGH is capable of rapidly expanding the limitations of a human being's body.
Jessica is not the only "special" affected by IGH. In Season 2, you'll see the impact of IGH on Jessica's life, and on other people afflicted with superpowers.
With the inclusion of a nefarious company like IGH, Jessica Jones challenges the conventional conception of superpowers as a positive thing. Jessica's powers were given to her, but they're not a gift. They're a burden, wrapped up with tragedy. If it were up to her, maybe she wouldn't be a super at all.