I have 4 kids. My eldest was diagnosed as PA (MFA actually) at 3 1/2, and Joey (my second oldest) is only 2 years younger, so until he was about 1 1/2, he had been exposed to a small amount of peanuts prior to that.
Joey got introduced to peanuts at preschool, because I forgot to tell the preschool that we weren't giving him them. He's never had allergy testing done because he seemed to have no other allergy problems and his eczemaa was so very mild. He's never had a lot of peanuts, tree nuts or shellfish, but he's had some exposure.
We've avoided peanuts, tree nuts and shellfish for Allison (third child). She had some allergy testing done... to confirm milk and dog allergies and to try to pin down whatever else was making her eczema flare so badly.
Ryan is 1 year old, and I plan on keeping him off peanuts, tree nuts and shellfish until he starts preschool. The only exposure he's had is through breastmilk. (I eat shellfish and almonds at restaurants when Jason is away for the weekend).
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Cheryl, mom to Jason (9 MFA including peanuts, tree nuts, shellfish and egg)
Joey (7 NKA)
Allison (4 milk allergic, suspect shellfish, avoiding PN/TN for now)
Ryan (1) nka *knock on wood*

I believe the stat is that having an identical twin w/ pa only gives u a 50% chance of being pa as well. luvmyboys