With the nutrition most of the world is getting filled with chemicals, pesticides, and GMO, it not only reduces nutritional value of food, but produces certain toxicity in the body which is accumulating over long periods of time (attributing to many 'modern illnesses'), and then take into account the amount of pills being popped (which are inherently toxic and will only increase the said toxicity with prolonged use, resulting in various medical problems ranging from internal organ damage, etc...) going on in the general population . I personally have no desire to have kids (can't stand them), nor do I see the point in having them.
The deterioration of the Y-chromosome is overstated. What is being lost from the Y-chromosome are genes that are present on other X-chromosomes. Essentially, redundant data is being eliminated, generation by generation. Thanks to how natural selection operates, if the Y breaks down to the point that it can no longer facilitate life or cannot produce a fertile male, then that male isn't having any offspring, and his genetic line is a dead end. Males without this affliction would, of course, be able to breed. Although it's conceivable that the Y-chromosome could someday break down to a point that it threatens the survival of the species, we're talking about something that's millions of years away--nothing we'll have to worry about in a timeframe relevant to humans. You'd better have some strong evidence for such bold statements.
This is a fallacy, well, numerous fallacies, created and perpetuated by marketing. Unless your kidneys are failing, "toxins" do not build up in your body. Marketing people came up with this idea to sell cleansing products (detox diets, juicers, vitamins, enemas, etc), but there is no scientific truth to the claim. Drugs can build up in the system, true, that is how some of them work. But every drug is different; some are completely out of the body within hours, for others it can be up to 6 months. If you're concerned about pill-popping building up in the system, I'd worry about what they're selling down at the naturopath's. There are a few substances that the body cannot process, and which will build up in a body even with a healthy renal system (some metals like silver, mercury, etc), and there are cases of people becoming seriously ill and dying from taking natural remedies like colloidal silver, causing heavy metal toxicity. The drugs sold as supplements, are not held to the same scientific standards as FDA approved drugs, so you never know what's really in them. I recently read report of a woman who died of all-natural arsenic poisoning because she thought sea kelp supplements were safe. This post displays a lot of chemical illiteracy: the first rule of toxicity is dosage -- anything is toxic in high enough doses (including water), and anything is safe in low enough doses. The important thing is not whether or not a substance is toxic, but at what dose it is toxic. As for nutritional value: the best designed and largest studies thus far have shown that there is no difference in nutritional value between organic produce and non-organic produce, so that statement is just incorrect. GMO's, of course, are highly debatable. My personal opinion is that there is not enough evidence to make any sure claim as to their value or safety. It is extremely difficult to research GMO's because finding unbiased evidence is hard -- it all seems to come either from big companies like Monsanto (an undeniably shady company) or from fear-mongering anti-GMO websites. The reality is, there just hasn't been enough time to know what the effects on human health (my guess is nil) or the environment (my guess is huge) will be.