  The fact that all kinds of entities are causally relevant to the synthesis of RNA might lead one to think there is causal parity among the causal elements. But this account shows that genes and DNA play a distinctive causal role in that genes are the causally specific actual difference makers of difference in the linear sequences of unprocessed RNA molecules. This distinctive role extends (with important qualifications) to the linear sequences of processed RNA molecules and polypeptides. The basic theory associated with molecular genetics, as distinguished from the fundamental theory, can be elucidated in causal terms.