In this book it explains that some people don't have the gene that is responsible for filter toxicins out of the body. You can find a environmental doc that can test you if they are willing, otherwise you have to see a doctor that follows his protocol and does the same blood tests as Shoemaker. He tests patients for this gene. I did get tested and I am missing this gene. Before I had the blood test I often wondered how people could live in moldy broken down houses and not be sick. My brother lives in New Orleans and let me tell you he has lived in some pretty moldy places and he is not sick like I am. Anyway if you want to learn more read that book or his latest book (can't recall the title). If bought my book off of amazon. I wish we could find a lab that could culture the molds in our body. I have searched and searched and haven't found a lab, so if someone does find one please share here.