Most of our degradation is environmental, however one must not forget the epigenetic factor and the fact that epigenetic expressions are inheritable. So you can fuck up your kid with toxins, and in the same process fuck up your bloodline because he'll pass this shit along. It's odd because it's super easy to fuck it up, but is a generational endeavour to unfuck it 

 Better yet are the time bombs which only manifest down the line. Like EE2 and fertility. If Gen 0 is blasted with a dose of EE2, subsequent generations have a continuous drop in fertility each generation despite themselves never being exposed. 

 that seems a bit hyperbolic; what is the route to causing fertility disuption? What I've heard that makes sense is that stuff like Ethinylestradiol are extremely stable and break down very slowly. Which is a problem, but not an unsolvable one. 

 Transgenerational epigenetic inheritance