Early on in our adoption process, we heard from other parents that our kids are part of an ethnic group prone to severe allergies to codeine. This turned out to be a misunderstanding, but after some research, we discovered that the phenomenon they were describing is that the incidence of individuals being ultrarapid metabolizers of codeine is much higher in their part of the world than ours. This would create greater risk for them - not just for the incidence of the genetic