That '70s Show followed a group of teenagers, but one character was noticeably younger than the rest. Jackie Burkhart, played by Mila Kunis for the duration of the Fox period sitcom, was a grade behind the rest of the gang. The series creators chose to portray Jackie as the younger member of the group for a good reason — one that made sense as time went on.

Jackie was the popular girl in school and the on-and-off girlfriend of Michael Kelso. Since Kelso was good friends with Eric Forman, Donna Pinciotti, Steven Hyde, and "Fez," Jackie found an in with the group. Though they didn't initially enjoy Jackie's presence, she eventually earned her spot at the typical hangout, Eric's basement. In time, she also became best friends with Donna and wound up dating Hyde and — most surprising, Fez — by series' end.

Related: What Mila Kunis Has Done Since That ‘70s Show Ended

When That '70s Show began, the sitcom was set in 1976 and the majority of the core characters were 16 years old. They were entering the rebellious stages of being a teenager, and though Jackie fit that mold, she was revealed to be a year younger than the rest of the group. This meant that she was only 15 when the show started, but due to her social status, she found herself in a number of cliques. The creators of the series never fully explained why they made Jackie younger than the others, but there were a few factors in front of and behind the camera that likely factored into the decision.

Why Jackie Being Younger Made Sense For That '70s Show

That 70s Show Jackie Burkhart 2

When Kunis auditioned for a role on That '70s Show, the actress was only 14 years old. This went against the 18 or older policy that the series put in place. When asked about her age, Kunis stated that she was turning 18 but didn't specify when. The crew later found out her true age, but they still deemed Kunis the perfect fit for the role, so they cast her despite the age difference among the rest of the cast. The rest of the actors she primarily worked alongside were hired based on the age policy and they looked older than her in the series, at least in the beginning. This was most likely why That '70s Show established her character to be younger from the outset.

The age difference between Jackie and her peers was also written into several storylines later in the series. Most of the gang was meant to graduate high school in season 5, whereas Jackie received her diploma a season later. Since she was still in school, this gave the rest of her friends the opportunity to attend the Snow Prom with her as a way to test their notoriety as adults now out of high school. Thankfully, for Kunis and That '70s Show, everything worked out in the end since she became a fan-favorite in the long-running series.

Next: That '70s Show: Every Major Inaccuracy From The Decade