... from the British Isles, and I'm lactose intolerant too. It happens.
My 23andMe health report detected the lactose intolerance, which confirmed what I already knew. I didn't realize it until the latter part of high school, though.
I was definitely more gassy than normal around that time, and it was always about when school was letting out. So I was eager to get home to privately release the pressure, and I had no desire to participate in after-school activities anymore. I was probably the best tennis player at my school (regularly playing against a much older brother for years), but I was embarrassed to tell the tennis coach why I wasn't going to play on the team.
Anyway, after many weekends and a Summer break, I realized it was only an afternoon problem for me after I had been at school. Then I finally narrowed it down to me always drinking those damn cartons of milk during my lunch break there!
I'd heard about lactose intolerance back then, but I assumed it was something deadly like a peanut allergy! I had no idea (pre-internet) that it could just turn someone into a flatulence machine!
My DNA ethnicity estimates: