We were discussing it in another thread. Possible scenario could be that Cora and Snow’s mother were sisters and rivals at the same time. Cora lost this rivalry and cursed Snow’s mother and her family (or something), the rage automatically got transferred onto Regina who could subconsciously hate Snow from the start but didn’t find an excuse until Daniel’s incident.
Another cool theory is that Snow’s mother was the White Queen from Wonderland which again would bring rivalry between her and the Queen of Hearts and would explain Cora’s connections to that land.
Can’t see that happening. Snow had no idea who Cora, Henry or Reggie were. She would have been introduced to Aunt Cora and Cousin Reggie if that were the case as there was no animosity between the families back then.