If they do that it means Regina married the man her mother had a daughter with, and I think it is too much ick for me. Incest is “in” I suppose with Flowers in the Attic gaining new cultural notoriety and of course Game of Throne’s Cersi and Jaimie but those are both intended to be dark, twisted stories rather than the more hopeful “happy endings” fairy tale tone that I sought in OUAT. The show does have its dark moments and twists but I guess all I can do is hope they won’t do it, because I can’t logically say they wouldn’t.
Besides the ick, it is just all kinds of “retconny” (how could he not recognize Cora years later when agreeing to marry her daughter?!)
Neal being Zelena’s half brother and therefore Regina and Neal are half-brother and sister is also a little icky but less than the above in my opinion. If Henry’s father is the half-brother of his mother’s step-grandmother it sounds bad but its not like Neal and Regina ever knew each other or treated each other like siblings, nor did Regina ever treat Emma as a step-granddaughter or think of Henry as other than her adopted son. I don’t know its just weird still.
Honestly the only combination that doesn’t “ick” me out a little is if EVA is related to Zelena, which makes Regina and Snow related (cousins), without the added ick factor. Eva’s brother could be Zelena’s father and the Wizard of Oz perhaps. It might explain Eva tripping Cora all those years ago , if she thought of her as “that tart who had the gall to break my brother’s heart”, not knowing the whole story perhaps of how Cora was pregnant, and run off by the royal parents. I don’t now, still soap-operaish but maybe a touch better.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass