As we trace the increase of complexity from single cell creatures, through small animals like worms and flies, and up to us, what we appear to be adding is control genes. Evolution is not so much adding new genes performing wholly new functions - what it's chiefly doing is to increase the variety and subtlety of genes that control other genes. Hundreds of genes appear to have come from bacteria - one of which is a major pathway for depression. We don't understand the mechanism of transfer, and indeed it's possible that the bacteria have picked up our genes rather than the other way round - though this seems less likely. But either way it's a tremendous reminder of the unity of life, and of the fact that we don't live in a cocoon isolated from other species.
Most mutations occur in males.
It's about a two-fold difference. More than one million SNPs have been identified. Overall, humans are 99.8 per cent genetically similar. The purpose of the 97 per cent of 'junk' DNA is being discovered. We have got stronger hints than before that the repeat family called Alu may play some important function.