I remember having had a little insight into this business quite a while ago. I had a piano student who was taking this GCSE ("give children simple exams"??) and he asked me if we might look over a paper together. And I was most amused by one question that has stuck in my memory. The candidates were given a snatch of music to listen to (probably a minute's worth or so) and then had to answer a multiple choice question (most of the exam falls into this category as far as I could tell) which - quite honestly - ran as follows:
Is this music:
a) raga
b) serial or 12-tone
c) reggae
d) baroque?
Need we say much more?
A little bit maybe. Being able to discern music of different genres is a rather basic skill, but not so basic that people will have been 'tested' on it before. That said, you say that they all were more or less in this category , so