Mercury affects everyone differently, but it definitely affects everyone. They may not know it, but the changes in their personality, energy levels, and other attributes are not be visible because they don't have the ability to compare their currently attributes to the way they would be if they had no mercury exposure.

Also, damage occurs in everyone to some degree, no matter how little you seem to be reacting to the mercury. It's just chemistry.

The people who don't seem to be having such reactions may also have different APO-E Genotypes. They may excrete mercury more efficiently.

Hope this helps.