Board Thread:General Discussion/@comment-26509198-20160713214402/@comment-24674051-20160718174137

No, it doesn't mean that she must have been in her 20's for Zelena. However, let's look at the broader picture for a minute (and yes, this is speculation and opinion).

Zelena was born was approximately 9 months after meeting Jonathan in the Tavern. Cora was, at that time, a serving wench. And one that was portrayed as somewhat naive in the ways of love (or at least lust and men), given that she was easily duped by Jonathan. Also, consider that Jonathan selected Cora from the available barmaids. Given his MO, he is not going to pick an older maiden. Jonathan is going to go for one that is young and naive. And if you last for any amount of time as a serving wench, you are not going to be naive. So all of the evidence would point to the notion that Cora was a young lady, most likely in her late teens or early 20's, when she met Jonathan.

Accepting that premise, The rest of pieces are somewhat easy to put in place. After abandoning Zelena, Cora could not return to the Tavern (where she was likely disgraced) so returned to her home and helped her father with mill deliveries (this part is obviously headcanon). This lasted for probably a year, which is when we get to the events in "Miller's Daughter" and her marriage to Henry Sr. and about 9 months to a year after that marraige we get the birth of Regina. "Sisters" happens around 10 or so years after that, "The Stable  Boy" probably another 8-10 years after that, and the Dark Curse another 8-10 years after that.

I would, personally, not put as much stock in the casting for "Sisters", as I agree that the show's execs went with what was available. (which is too bad, because it would have been great to have both Rose and Barbara in that episode).