If you mix up different flavors of Jelly Belly jelly beans, will similar flavors clump together? I believe this myth has to do with different densities. Suppose when the Jelly Belly beans are mixed together, that they are mixed in a plastic bag that one would get from a candy store.

I'm not sure what you mean by different flavors clumping together. You can buy variety packs of Jelly Belly beans which have a wide variety of flavors all mixed together and none of them ever "clump" as you stated. In fact, by coincidence, I finished eating a bag of Jelly Belly jelly beans earlier today! They were the Soda Pop flavors. Guess what?..... None of them were clumped together!

I think it's similar to the line from the movie "I, Robot" where they say that robots left unattended will tend to group (clump) together.