Uh-oh...I missed Martha. Of course, Oprah slipped up once by trusting an author who appeared on her show...but I'd better not take any chances. Martha is by definition correct. ;^D
Scientists have a very hard time with proofs like that. They can prove that this reindeer and that reindeer can't fly...Pushing 'em off the roof will do that. But they can't prove that no reindeer can fly. They'd run out of reindeer.
I've thought about the snowflake business, myself. I figure the folks who claim that no two are alike must be talking about patterns down to the molecular level. And at that point, who cares?
I have enough trouble these days telling apart people, so the individuality of snow flakes is pretty much lost on me.