Board Thread:Spoilers!/@comment-2153169-20140402112823/@comment-24589671-20140416132207

Billyc84 wrote: If Leopold had a child with Cora(Zelena) then surely he would have known who she was when he met Regina(and possibly Cora) for the first time in the house, in the stable boy, he would have felt weird marrying the daughter of a woman he had a child with.... Just seems really weird to me.

Considering Killian fell in love with Rumple's wife then the women Rumple's son fell in love with it doesn't seem that far fetched. Remember trying to figure out the family tree on OUaT is like trying to find one grain of salt in the sugar bowl.