Star Trek: Deep Space Nine1993

Quark:
Don't you get it, Odo? We humanoids are a product of millions of years of evolution. Our ancestors learned the hard way that what you don't know might kill you. They wouldn't have survived if they hadn't jumped back when they encountered a snake coiled in the muck; and now, millions of years later, that instinct is still there. It's genetic. Our tolerance to other life forms doesn't extend beyond the two-arm, two-leg variety. I hate to break this to you; but when you're in your natural state, you're more than our poor old genes can handle.