Just watched an interesting presentation by Shanna Swan, who has a book out on this exact topic[0]. I haven't looked into the veracity of her claims but basical

Just watched an interesting presentation by Shanna Swan, who has a book out on this exact topic[0]. I haven't looked into the veracity of her claims but basically her argument is as follows: TL;DR - its chemicals in the environment, particularly those that disrupt hormone production in utero. - Sperm count and testerone levels having been falling at a rate of about ~1% per year. This also coincides with cases of miscarriage and erectile disfunction rising at a rate of about ~1% per year. - This suggests something is affecting the human reproductive system. - Three possible factors could include genetics (not likely since the change is too rapid to be evolutionary), lifestyle (certainly a factor), and but also potentially environmental - Hormonal disruption from environmental chemicals has the most lasting effect when children are in utero, particularly any chemicals altering testosterone production. Testosterone is important because, biologically, female is the default. In the absence of sufficient levels of testosterone in utero, male children will have underdeveloped masculine traits (biologically, not psychologically). - One measure of underdeveloped masculine traits is anogenital distance (look it up, but not at work if your really curious). Phthalates is one class of chemical that has been demostrated in rats to disrupt in utero testosterone production and reduce anogenital distance. There is growing evidence this also occurs in humans. - Phthalates are used extensively in a number of products, including food products (basically anything with soft plastic) - Other classes of chemicals exist which also disrupt hormone function. These hormone disruptors have an even more pronounced effect when combined together. [0] https://youtu.be/Uo-kSxHNSDQ https://youtu.be/Uo-kSxHNSDQ