How long did you delay for? It's not like there's some tiny window of opportunity before 10 months or whatever. Consider that the Spanish conquistadors who literally never saw a peanut as a child and tried their first peanuts as adults all survived long enough to make peanuts a globally accepted food. You can't blame yourself. To think that somehow not delivering peanut exposure was a sure cause of the allergy is nonsense.
Prior to modern hygiene, most humans probably had worms, as well as having to constantly battle other pathogens. Immune systems had no time for peanuts in the face of these other threats.
We don't have records from the areas where peanuts were consumed prior to the 19th century (because the Spanish systematically destroyed records during the conquest of South America), so I'm not sure how we would know if there were peanut allergies prior to modern hygiene.
I don't remember exactly, but I suspect that the introduction and then disappearance was worse than not introducing it at all until we could do it consistently. It was probably something like six weeks between giving up on peanut butter in her milk and starting her on solid food.
I'm not aware of a recommendation to give peanuts/other possible allergens that regularly, at least I'm certain that's not a thing where I live. The change was that peanuts before were avoided completely for years, and now they are added when it fits, like a peanut butter toast once in a while. Outside of the desensitization therapy you go through now, you do not give like two peanuts every day or put it in milk regularly. You just test for allergic reaction early and then stop thinking about it, that's the change.
So you did nothing wrong. The six week pause was completely meaningless.
