1. Do they have enough persistance to learn and then tackle problems 2. Do they even care?
Most people just aren't wired that way and it's nice enough if you find someone who's even willing to listen to you talk about technical things
However, I strongly disagree with the popular notion that most people "just aren't wired that way" and can't learn to program. Certainly some people take to it much more quickly than average, but dismissing everyone else as doomed to never be able to comprehend the cosmic complexity of a while loop because their brains are fundamentally less than ours is kind of terrible.
Most people are't wired to learn how to program effectively, just as most people aren't wired to be a mechanical engineer or a chemist or a doctor.
I don't want to sound like an elitist asshole, but it does require an above average intellect (oh wow I sound like a neckbeard here) to be able to do any of the above. That immediately disqualifies half the population.
Most of my friends cannot and will not become software engineers (or engineers of any kind), and that's fine. I don't know why they'd want to.