It was surprising to see that the camel has two humps, that is, one part of the population seems to be incapable of learning programming, while the other is.

The study you're probably thinking of failed to replicate with a larger sample size. While success at learning to code can be predicted somewhat, the discrepancies are not that strong.

http://www.eis.mdx.ac.uk/research/PhDArea/saeed/

The researcher didn't distinguish the conjectured cause (bimodal differences in students' ability to form models of computation) from other possible causes. (Just to name one: some students are more confident; confident students respond more consistently rather than hedging their answers; and teachers of computing tend to reward confidence).

And the researcher's advisor later described his enthusiasm for the study as "prescription-drug induced over-hyping" of the results ...

Clearly further research is needed. It should probably not assume that programmers are magic special people, no matter how appealing that notion is to many programmers.