Honey is made from pollen. By eating honey you are injgesting pollen in a form that doesn't actuate the symptoms of hay fever. However, your body does become accustomed to the complex chemicals in the pollen and as a result you become desensitised to them.
When you later enconter pollen in the air, you are less likely to get the physical reactions we describe as hay fever. Honey is a home remedy that can really help your family.
The pollen you enconter in your local area is different from pollens in other lands. You should buy local honey if you wish to desensitise yourself to the local pollen. If you move house, and go to a different part of the country (for instance moving from a town in a flat lowland environment to a village in the mountains) then make sure that your family (and particularly the children) regularly eat some honey on toast regularly for the first year of living there.
Don't overdo it and make sure they brush their teeth well. Don't let the kids think of it as medicine, just a regular part of breakfast.