[asher]

I suspect that at least two aptitudes are involved, and different programming languages/platforms place different demands on those two aptitudes.

One aptitude is essentially the math/engineering ability. The other is linguistic.

[ds9]

Also the working memory and a certain willingness to sit there doing purely mental work for significant periods of time (well I guess the latter is part of 'math/engineering ability'). The working memory aspect is what makes this sub-thread not a complete digression.