It is known that the majority of the human genome consists of repeated
sequences. Furthermore, it is believed that a significant part of the rest of
the genome also originated from repeated sequences and has mutated to its
current form. In this paper, we investigate the possibility of constructing an
exponentially large number of sequences from a short initial sequence and
simple replication rules, including those resembling genomic replication
processes. In other words, our goal is to find out the capacity, or the
expressive power, of these string-replication systems. Our results include
exact capacities, and bounds on the capacities, of four fundamental
string-replication systems.