People have known for thousands of years that humans and animals can acquire strong, lifelong desires for things that defy human expectations of how the universe is supposed to work. Modern science has only been studying it for about 70 years now, but the research shows these things are probably more common than most people suspect; so common that it seems likely to be the result of a process that humans and animals go through as a natural part of their early development. Individually, things like diaper love or balloon fetishes may not be very common among the population but, collectively, nearly everyone is directly affected by this process and acquires a range of strong, specific desires because of it.