Epigentics is a sciencey word, I know. Real, true, chemistry/physics/etc isn't really my thing. Or it is, as long as it's fairly simple and can be applied practically to my life. Epigenetics is kind of on this line- it's extremely theoretical still, and is very complex, but I also feel it explains a) why it is important for me to feed my family the way I do, and b) a huge cause of all the chronic illnesses we suffer from, including (and especially) the huge rise in infertillity.
Basically, epigenetics is the belief that what we eat and are exposed to affects not only our health, but the structural genetic makeup of our children and their children.
How can that be? Well, while my understanding extends beyond that, my ability to explain it does not. Which is why I am linking you now to this excellent post from Real Food Forager- Epigenetics: Beyond Heredity. Don't worry, she manages to explain it in simply without dumbing it down too much.
This is my strongest argument against vegetarian and lowfat diets. Despite my opinion of the diet, I respect vegetarians (despite the fact that I called a very outspoken vegetarian commenting on this post immature... ). They have given thought to their food and where it comes from. But I view it as a stop on a journey on the way to where I am now- the realization that it is possible to eat humanely raised meat, and that it is actually healthier to do so. Pay special attention to the bits about methionine and it's affect on genes. Methionine is almost exclusively found in liver and eggs, although very small amounts are found in leafy greens (but as is the case in many of the nutrients found in small amounts in vegetables, in such low amounts that it would be nearly impossible to get enough of them).
The thing that bugs me about vegetarians- they don't listen. Nearly everyone I know who follows a traditional foods diet or an organic diet including grassfed meats was once a vegetarian or vegan, or at the very least was at a point in their journey where they believed the China Study and the current mainstream medical view that "eating animal products = heart disease" even if they lacked the conviction to fully give up meat. Then they have moved on, almost always because the diet made them feel like poo poo. So going onto a traditional foods blog and preaching the benefits of avoiding animal foods and eating vegetable oils is horribly annoying, not to mention pointless.
But I'm digressing. Check out the link on epigenetics. Or just go eat some eggs and rest easy knowing your children and their children will be able to procreate. Natural selection will rein.