I don't know if there is or if there is not any disposition or genetic element but if it applies to one, it applies to the other. There are people who, even with effort, fail to "get" programming (or, more specifically, the logical concepts behind it) in the same way that you're struggling with the physical aspects of the guitar.

I've had to do quite a lot of DIY as a home owner but I still feel as useless and incompetent as I did years ago. The difference between DIY, though, and programming is that the average joe doesn't have to program whereas I still have to do house repairs.. :-)