Those are normal human reactions and emotions, you cannot put them into a group such as kids and label other childish for acting so.
Wrong, as human adults you solve out the problems rather than saying,
'I won't do this if you do this,' which is childish. You can't play reactions and emotions into physiological way of thinking. G36E is right, you're being childish, why you don't seem to agree to it and most likely will come up with a bullshit answer to make up for it.
And yes we can, as human nature we have a set age limit of how our brain works, saying. "I will not do this because of this," is childish because most grown adult will not fuss over a video game and do something more productive and if you DID come to an agreement, I didn't know and wanted to post your flaw out.
Being called childish does not mean you're acting like a child, it means you're thinking or behavior is like that of a child, which is what you're doing.