When I think about what a complicated piece of machinery the human body is, it seems there must be millions of potential ways for things to go wrong in the development of a baby. However, babies are typically born perfectly healthy, birth defects are rare, and this blows my mind a bit. Is it understood how this has become possible? I'm talking about an actual mechanism that ensures the DNA blueprint is so accurately followed. I mean, it takes us quite a bit of effort just to grow a uniform crystal in a lab, so when we're talking about the huge variety of different molecules that have all somehow got to take the shape of a normal baby... all those different types of cells in such precise configurations... there must be something interesting happening to make that all go smoothly?