I'm having a hard time understanding exactly what you want from your query. Can you detail it in some sort of pseudocode instead of a sentence? (For example, do any of the nodes in this example graph match your query criteria? If ‘Ann’ is a match, is it because all of her parents which have a birth country have the same birth country? Or is it because all of her non-adoptive parents have the same birth country? Or is it that she has at least two parents with the same birth country?)

What I want is for Ann to be returned because all her Parents are from the USA.

The reason why I introduced "adoptive" parents is because: 1- This is an example (I'm not actually working with a Graph with parents ;) ) 2 - I wanted to make it clear that you do not know how many parents a person has -> so has not to accept "counting 2" strategies. Maybe I should have a picked a complete abstract example.

So should Steve be linked to USA in the graph then?

Of course... Really sorry about that. Updated the picture