Is it learned or in their innate?

So Jett has continued his funny lines and for most of it we have to turn and laugh. Were does he come up with this stuff? Example: The other day I was in the kitchen making dinner and Jett comes running in...
"Mommy, I have something for you!"
I turn, expecting something cute, but instead he just turns around bends over and toots.
I mean seriously, where does he come up with this stuff. Crazy kid.

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Brayden fell asleep on the couch a few days ago without me knowing and Jett comes up to tell me.
"Mommy, Brayden fell asleep, but I took care of him. He's okay now."
Yes, immediately red flags go up and I run over to the couch searching for Brayden. I removed the blanket and this is what I found. Jett put all the pillows around him, put all the coasters on his head and then threw a blanket over all of him. The kid didn't even stir. Not even when Greg and I were laughing at the sight.