How similar is human DNA to other species?

Humans and chimpanzees differ at about 1.2% of positions where their genomes line up, so about 98.8% identical; counting insertions and deletions widens the gap to around 4%. About 85% of mouse genes have a human counterpart. The 'half our DNA is shared with bananas' line refers to the share of human genes with some banana equivalent, not identical sequence. Only about 1.5% of the human genome codes for protein.

Source: Chimpanzee Sequencing and Analysis Consortium (2005), Nature; Mouse Genome Sequencing Consortium (2002), Nature