Did eating a lot of 'bad'' things when I was a kid, make my immune system stronger?

[Scarlet J Rose]

I ate a lot of things like dirt, ants, slugs, bugs etc when I was a toddler and now I am rarely sick. I get a bit of a cold about once a year and have never had the mumps, chicken pox, the measles or anything of that sort. Explain to me how this works?