I have a shaky understanding of "non-shared environment", I get the sense that it is based on the context of the study. e.g. If I do a study on genetically iden

I have a shaky understanding of "non-shared environment", I get the sense that it is based on the context of the study. e.g. If I do a study on genetically identical mice and control their sugar intake, "sugar intake" would be shared environment and something like "exposure to lead" would be non-shared. If I did the same study and controlled their exposure to lead, it would be "shared" in that case. Is that an accurate understanding? Is "non-shared environment" basically the "everything else" category after genetics and shared environment have been controlled for? Also, > If clones in as exactly identical environments as researchers can create and perceive still wind up with such dramatic individual differences, how is science even possible on what causes the differences? Another point in favor of simulation theory? :)