Thing is, people are convinced that DNA is the be-all and end all of genetics. Some kind of 'recipe' for making biological life.
That's not strictly the truth, it's more like a recipe without values, it doesn't tell you how much of things are needed, or how long or in what conditions the egg should remain in the womb etc, none of that information is in DNA.
There is also stuff called 'Junk DNA', a rather poorly named collection of data that we aren't quite sure what it does. Giving it the name 'Junk' has scary implications, since no-one is actually sure whether they are junk or not.
Another good example is Yeast. It cannot reproduce without external genes to nudge proteins into the correct place, same with humans, the entire DNA string does not contain enough information to even map 1 millionth of the neural pathways of a newborn child, external forces play a huge role in matters.