There's a phrase that I've been hearing a lot lately in corporate contexts that's becoming a bit of a pet peeve of mine. It's "[Insert positive quality here] is in our DNA," as an attempt to convey, "[Positive quality] is part of the essence of who we are." I've been thinking about why it bugs me so much. It reinforces a kind of casual biological determinism that I'm not really fond of in general, but I think the real thing is that the metaphor gets weird if you actually have more than a casual understanding of how DNA works.
The thing about DNA is that it doesn't, by itself, do anything. DNA has to be expressed and translated into RNA or protein in order to have an effect. And a huge amount of our DNA (up to 90% by some estimates) is never translated. Excellence may be in my DNA, but so are the mangled bits of feline retroviruses that generations of my ancestors picked up from their pet cats.
Even bits of DNA that could be translated can have their expression regulated up or down or switched off entirely by environmental factors. And genes rarely work like the simple dominant/recessive Mendelian pairs from your high school biology homework where you had to figure out how many of a given couple's offspring would have blue eyes. You've got traits controlled by dozens of genes, working together in complicated ways. So a trait may be in your DNA, but whether it's in you is the result of a messy process influenced by other things in your DNA, your environment, and your own behavior.
Hmmm...maybe it's actually a better metaphor than I thought.