Can AI recognize fake smiles?

Context:
So, my good-for-nothing brother-in-law comes with his toddler. I'm pissed at him for reasons, but gentlemen are always polite IRL and look at each other for greetings.
His toddler has always loved me and runs towards me. But see my fake-ass smile and suddenly she is shy and nervous.
She has noticed the stealth-fake smile that fooled her mother and grandmother.

Can AI do that? are there enough markers to differentiate a fake smile from a real one? Or is it waaay to personal?
If is it trivial, can someone please make a fake-smile coach app?