DS hasn't had any history of food allergies. My SIL claims that our nephew has a peanut allergy-every time he eats peanut butter or something with peanut he supposedly vomits.

Someone was telling me the other day they gave their LO a PBJ sandwich for lunch and their LO is about the same age as mine (15 months) and I was surprised but didn't say anything. When did you introduce nuts, specifically peanuts?