While I agree that everyone CAN learn anything, it doesn't mean they want to. Motivation is a big factor.

And when it comes to software development, the actual writing code part of it, I'm confident you need to have a knack for it.

Mind you, there's plenty of jobs in software engineering that don't involve writing code. We're desperately looking for a manager for example, because our current "self-managing" team is far from effective.