ah ok. I know what you mean now. Actually I may have a very good and easy example for this, hope it worksJeroen wrote: It says, in short, that quarks cannot be obvserved directly, hence the statement that they are 100% identical is not proven.

Yes, they can´t be observed, but only because they can´t be seen, doesn´t mean they can´t be detected, tasted, smelled, even heared. You know what I mean? Like with the p h a rmacy pill. Does the same thing every time you take it. And it doesn´t matter if you produce it out of a plant or even a dead pig lying around for 1 year. It always does the same thing, because it is a molecule consisting of a defined structure. As long as you hold on to that defined structure, you can produce it out of whatever you want (of course the atoms in the structure of this molecule have to be inside the thing you want to produce it of^^).
Another thing is: If atoms are each the same 1:1, then everything they consist of is, too. So that would mean Quarks are also the same, otherwise atoms would show a reaction of difference when you work with them.