Sure, but some causes of infertility are correlated and persistent. If I'm exposed to poisons in the air or water, it's likely to happen to others as well - es

Sure, but some causes of infertility are correlated and persistent. If I'm exposed to poisons in the air or water, it's likely to happen to others as well - especially if it's at levels where it's not immediately noticed. Many other causes of effective infertility are unlikely to impact entire groups of people across long periods of time.