While our genetics (combined with our environmental influences) offer explanations for a large amount of variation in humans, the increasing use of our genetic make-up as a way of passing the blame for our behaviour is actually quite worrying. On a small scale, it's quite nice to say "well, nature made me this way". I like to use my biologically programmed body clock as an excuse for sleeping in late, and trying to claim that I'm snappy and impatient because "it's in my genes" would be tempting (who knows if that would even be possible). Criminal behaviour, however, is a whole other story. We can't really use our genetics as an excuse for murder... can we?