I have a grandson that just turned 4 y/o. No way does he act or talk like a two year old. I have personally seen CMs at the turnstyle ask kids how old they are. At least once (at DS) the kid said he was three. The parents tried to cover and say he was actually two. The CM laughed, but pointed over toward GS and told the parents to buy the kid a ticket. Sorry, but no way, can you pass a four y/o off as a two y/o.
I've also heard a waiter at CP supposedly just making conversation with a kid at the table right next to us. He asked the kid how old he was and the kid said "eleven', then apparently realized his mistake and said 'no, I'm ten, no I mean I'm nine. Oh, sorry! How old am I supposed to be this trip dad?". It was really sad, but funny at the same time. After the waiter walked off, the dad really tore into the poor kid. We felt so sorry, for him, but felt the family deserved what they got, for trying to lie about the kid's age. This was a really small eleven y/o, by the way. They were charged the adult price for him. We knew because the dad got really angry with the kid when they got their ticket.