I would strongly suspect that 
  just as math and CS ability are correlated, 
  so would math and chemistry. 

I am not sure about that. In my experience, mathematics and chemistry were not noticeably correlated (either way). On the other hand, such ostensibly different subjects as mathematics and music were positively correlated. Experience is anecdotal but includes math classes in high school, applied math in college, and computer science in grad school.