If you have already gone through the trial, error and sometimes absolute horror of food allergy testing, and found out your kid is allergic to certain foods, you may be keen to get your other kids tested, too. After all, allergies (or allergic tendencies) seem to run in families, so it's logical, right?
Turns out, it may not be that imperative to test sibs—unless and until they have a reaction. A recent study presented at the American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting states that only 13 percent of siblings have an actual food allergy.
As such, the study authors are recommending that food allergy screening not happen before introducing a sibling to a potentially-allergenic food. One reason being the low rate of siblings who actually have a food allergy, and another is that testing before you've tried the food tends to not be an accurate predictor of whether you'll be allergic to it or not.
As a mom of kids with food allergies, this topic is near and dear to my heart. My husband and I have a few random allergies—cats, dogs, and pollens for the most part—but even so, we were pretty surprised when our second kid popped up with a peanut allergy. It seemed to come from basically nowhere, but then we learned that if you have allergies of any sort, that tendency can be passed along to your children.
So, in my opinion, you should take this information with a grain of salt. If you're not comfortable "waiting to see" if your child has a reaction, then by all means book an appointment with an allergist...
So that surprise led us to learning all the ins and outs of food allergies—how we needed to read labels (and we are really good at it now, after 12+ years) and how serious the allergy can be. But once his two younger sisters came along, I was, in particular, way more paranoid about killing them by letting them try peanuts. Or anything, really, at all.
We had our first daughter preemptively tested for food allergies, and while she was positive to peanuts despite never eating them, she was able to test out of the allergy in kindergarten. As a side note, she was soon after diagnosed with celiac disease, so she wasn't able to enjoy eating freely for long.
My second daughter, however, had shown signs of allergic reactions (hives) to both dairy and eggs when she was still a toddler, and I didn't dare "test" her with actual nuts or tree nuts to see if she was allergic. Instead, we booked an appointment with a pediatric allergist, and had her blood drawn and had her undergo a skin prick test.
She tested positive to milk and eggs, but also peanuts and several tree nuts. She has since had a reaction to an accidental exposure to peanuts, and we carry epinephrine auto injectors everywhere we go, as we did for our older boy.
So, in my opinion, you should take this information with a grain of salt. If you're not comfortable "waiting to see" if your child has a reaction, then by all means book an appointment with an allergist—as long as you're aware that you may get a false negative if they haven't been exposed to the allergen before.