"____ neither cares nor knows. ____ just is. And we dance to its music.” (Richard Dawkins) (3)
I believe the answer is:
dna
(Other definitions for dna that I've seen before include "Substance that stores genetic information in body" , "Double-helix molecule (abbr.)" , "Substance that stores genetic information - often used by police" , "Initially, it stores genetic information" , "Genetic carrier" .)