Well, I think I've got a knock-out argument against evolution, and the creationists are welcome to it. The dagger in Darwin's heart? Kids.
Now I know what you're thinking: isn't, like, everything about kids an argument in favor of heredity and, therefore, evolution? Sure, they look like us, they often sound like us, take up similar interests, and have an annoying tendency to replicate our own annoying tendencies.
But here's the thing. If evolution by natural selection was really a thing, it would suggest that children should be little sponges that learn everything they can and trust their parents completely. In my experience, that is far from the case. If I was a stay-at-home cave-dad in paleolithic times, Beans (our 2-year-old) would not have made it much past two. The first time we saw a saber-tooth tiger and I said "Run!" she would be all "No! I don't want to run away!" And I would say "But we'll be eaten by the tiger!" And she would say "I. Don't. Want. To. Run." And she would die of stubbornness and I would die of embarrassment that I couldn't even parent my cave-toddler into avoiding obvious dangers.
Or I would tell her she needed to eat the mastodon I'd killed, or the twigs and berries I'd foraged, and she'd be all "Yuck!" because she only wants mac 'n' cheese or fig bars, and neither had been invented yet.
So there you go. Check mate, Professor Dawkins.