I think they're more looking for a sign that you had an early and therefore natural curiosity to tinker with the mechanisms in the world. Not "CS" per se, but just... computer tinkering. If your family couldn't afford a computer, IMHO, if you at least, say, took a clock or motor apart or something, that would be a good indicator, too.

By the way, this has been brought up as the reason for the dropoff in the women who enter CS curricula in college. Ever since home PC's became affordable, freshman CS classes have basically assumed prior (and thorough) computer experience, and many women who might otherwise become good programmers, for whatever reason (society influence, etc.) have had waaaay less hands-on time with computers than boys, when they become freshmen.

That said, I have met some excellent programmers who started out doing something that is superficially completely different (musicians, for example).