We knew that we would get our daughter tested for allergies eventually since they run in the family. However, before we could get her tested (she was four yrs old), we found out about her tree nut (not peanut) allergy when I gave her a walnut (for the millionth time) and she started breaking out in hives and going into anaphylactic shock. She'd been eating nuts of some kind or another her whole life with no reaction at all (and I was pretty conscious about monitoring it because my son has peanut allergies and I know what to look for), but for some reason, that time it finally triggered an allergic reaction and could have been life-threatening. We were at the mall when it happened and luckily it's close to home, so I rushed her back and gave her a dose of Benadryl. It kicked in after about 1/2 hr and everything was alright, but she was starting to get a runny nose and start coughing about 15 minutes after eating the walnut. The doc later said those are the initial stages of anaphylactic shock and without the Benadryl she could have really been in trouble. When we had her tested for allergies after that, it turned out she was allergic to tree nuts (severely), cats, dogs and some grasses (no big surprise there). We now carry around an Epi-pen with us just in case. It was so weird to me how she could eat pecans and pistachios and even walnuts for YEARS with no problem, then BAM, allergic reaction! Doc said it sometimes happens that way...so I guess there's no real way to tell if your child has a nut allergy until you get tested for it. If allergies run in your family, you should get your kids tested anyway, their chances go way up if you or their father have allergies. I wish I'd gotten my daughter tested sooner and avoided her near-miss. She'd also been around dogs without reaction, too. My son is allergic to milk, but has no outward physical reaction to it (he does get grumpy and it wreaks havoc on his digestive system). I would never have known of these allergies if I'd never gotten them tested. My other daughter did get tested for allergies a couple of years ago and everything came back negative. Well, we had her tested again two weeks ago, and found she'd developed seasonal allergies (grass, pollen) and an allergy to cats. She tested negative for cats 2 years ago! It's hard to keep track of, but basically, if you have allergies of some kind, chances are your kids do too. Good luck!