Board Thread:Show-Related Questions and Answers/@comment-24.128.131.119-20130218041312/@comment-4839682-20130218041648

Basically, since Regina was formerly Snow's step mother, David included her family, making it go a bit like this:

Henry's parents are obviously Neal/Baelfire and Emma

Henry's grandparents by birth, then, are Rumplestiltskin, Milah, Snow, and Charming

His great grandparents by birth, that we have seen, are Ruth and Leopold

David also included Regina as Snow's step mom, which would make Regina his step great grandmother, and Cora and Henry Sr his step great great grandparents

By adoption, Regina is his mother, and Cora and Henry Sr his grandparents.

Note though that all those step ties have been severed.