Your genome is not a static collection of DNA nucleotides; rather it is a dynamic system subject to evolutionary selection. It is for this reason that the DNA content is so variable in different species. But the genome size is not always an indication of the complexity of the organism, proven by the fact that both humans and mice have roughly about the same genome size � about 3 billion nucleotide base pairs.
The number of genes also contributes to the difference in DNA content between species. In addition, the genetic composition of the genomes can vary greatly � some species have more elements like noncoding DNA and some have less.
These differences in DNA content make it difficult to correlate genome size to complexity. Thus, despite having 50 times more DNA bases than humans, the beautiful flower Paris japonica is only just a flower.