Hygiene Hypothesis

This hypothesis suggests that children who grow up in too clean of an environment do not develop the natural antibodies they need so they are more prone to becoming allergic to common bacteria. These children are supposedly more susceptible to microorganisms because they have never been exposed to common bacteria that would have promoted their own antibody growth.
A home that is too clean is one that uses nothing but antibacterial soaps, detergents, and cleaning agents. The children from these homes do not play with animals, they do not play in bare-feet, and they are not generally allowed to get dirty.
Children who never have an exposure to the normal bacteria we come in contact with on a regular basis are more prone to allergies and to both eczema and asthma. This suggests that children who are allowed to get dirty are often healthier than the cleaner children are.

Dishwashers

Dishwasher washes dishes using water that is hotter than the water that is used by people washing their dishes by hand. Naturally, a human cannot put their hands into water that is as hot as what can be run through a machine. For this reason, it is surmised that dishes cleaned in a dishwasher have fewer germs on them than dishes that are cleansed by hand. The germs are the less exposure to common bacteria and the increased number of allergies.
Children that live in households that do not own dishwashers are exposed to more bacteria, and therefore, their antibodies are more capable of fighting off allergies, and microorganisms that would make them sick. The children from these households also have fewer colds, and other common childhood ailments than the children who live in homes with dishwashers.

Fermented and farm fresh foods

To prove the hypothesis parents of children who ate few fermented or farm fresh foods and parents of children who ate fermented and farm fresh foods on a regular basis were polled. The children who were eating more of the fermented and farm fresh foods have fewer allergies than the other children.
This information suggests that the hypothesis that children eating foods that were pollinated with local flower nectar were exposed to the local pollutants and this reduced the number of allergies that the children had because they grew immune to the local pollutants through their repeated exposure.
The healthiest children were reportedly living in homes that ate locally grown fresh fruits and produce, ate fermented foods regularly, and washed their dishes by hand. The majority of these homes also allowed the children to play freely out of doors, and often opened the windows of their homes to provide fresh air to the interior portions of the house.

More research is needed

The correlation between a home being too clean and the allergies the children suffer is only a hypothesis, even though it is an interesting one. More research will be needed before pediatricians begin to suggest that you get your child dirty to keep them healthy.