The amount of a toxin a person is exposed to at any point in their lifetime, not necessarily their present toxic load (total body burden), gets passed through your epigenetic code to posterity so they’re affected at a “geometrically” higher level from the same amount of toxin. And this happens whether either parent or child reduces their overall toxic load at some point in their lives, or not. For instance, scientists have found the first generation of frogs exposed to a given quantity of mercury display ‘X’ level of injury/mutation. But the damage done by that same amount of heavy metal doubles in the second generation, and doubles again in the third generation until none of them survive. Instead of gaining a tolerance, as is common with many biological processes, they developed a dramatically greater intolerance with each exposure due to alterations in how toxins epigenetically affect gene expression. They display increased sensitivity in future generations that makes them far weaker in fighting off environmental threats, recovering from health challenges, and normalizing genetic defects.