I have a question about food allergies and this way of eating:

I understand about some of the common food allergies, milk, peanuts,
gluten/wheat as being foreign proteins etc.  I can't figure out about 2
other items, seafood, which alot of people are allergic to and soy (soy
milk) which is given to people who are allergic to milk.

Can anyone explain the differences?

Thanks,

Dan L.