I happen to know (due to job), that many adults have problems grasping for loops (in Python) when learning programming. It is one of the main points where problems arise in programming introductions. It may all depend on how it is explained for what person, as different people understand different explanations better than others. Or it may be syntax related. Or that people for the first time fathom how they can make the computer do things in such a time saving manner. Who knows.