I think it’s near impossible to fake being genuine.
For most people, our bodies are very good at knowing when someone is genuine, when they are acting trustworthy, etc
There are many known visible signals you can look for (like symmetry in a smile means it’s genuine, body language etc)
But I think there’s way more that we don’t know. There’s a lot of ways in which we know that someone is NOT genuine, but we can’t articulate it, because we’re not even consciously aware of it
I think one corroborating piece of evidence here is actors. The best actors don’t “pretend” to be a role, as much as they try to really believe they are the role. It’s really the only way to capture something so complex that you yourself don’t even understand it.
We can’t fake it because we don’t (yet) fully understand it. So the only way to do it is to genuinely believe it.
And at that point, is it fake? (I think not. It’s sort of like giving a thief your money so they don’t steal it)