We have said and we have heard it.
Those ungrateful kids/children's don't appreciate the things we/(I) do.

Now, wait?
As adults hadn't we heard that phrase too?
When we request more than we should from parents.
Or they sacrifice for us to get something we adore.

Or without our knowledge buy us something to which we show dislike.

More likely, you gonna hear those ungrateful kids.
And let's admit it, we were.

And then we inherited them through birth.
****!