I didn't realize how similar they were to pawpaws! That's so interesting, thank you for this picture.
I'm Googling and I don't think they're actually related. They're from totally different parts of the world. But it's probably another excellent example of convergent evolution.
Idk man, I think it has to do more with size rather than seeded/seedless. I've had small and large bananas both, all seedless. Small ones are always straight, big ones always curved. It's just how they grow out of the petals.
Hang out with it long enough to see it drunk, then report back on whether it's still looks perfectly straight or not.