The number of genes in the human genome, according to the most recent analysis by a group out of MIT/Harvard.
This is down from old-school estimates of 150,000 and moderately lower than the numbers hypothesized after the Human Genome Project (35,000).
The new analysis uses a way of comparing many species in order to predict what is and isn’t a gene in the human genome, since we don’t know how to ID them in a foolproof manner yet.
So there you have it, every cell in your body has ~20,500 tools in its toolbox to make it . . well, IT and you … well YOU. It’s all in the combinations.