There are some basic reasons why people sometimes have problems with tropical fruits. Most temperate climate fruits come only from the rose family. However, tropical fruits come from many different families of plants, some of which have unedible relatives in temperate zones. For example... cashews are related to the poison ivy and poison oak family, and therefore give some people reactions. In general, if you and your ancestors came from a temperate climate, your body is not used to being dependant on these tropical fruits for nutrition, and there is always a possibility that you will be unable to handle eating them.