A person's genome, epigenetic profile, physical environment, social environment, microbiome, parasite-ome, neural connectome, metabolism, enteric connectome, an

A person's genome, epigenetic profile, physical environment, social environment, microbiome, parasite-ome, neural connectome, metabolism, enteric connectome, and diet are all unique. Some of these factors regulate the others; some have two-way regulation. There are far more combinations and variations of the above variables and sub-variables than can be tested for in clinical trials. This fact means that some obscure combination of these variables may result in unintended negative (or positive, less frequently) consequences upon consumption. Theoretically, you could test for differences in the 1000th person-- with today's technology, it would be a test which described the person's genome. Once scientists had that genomic data in hand, they'd certainly find a profile of alleles which could feasibly describe why a negative reaction occurred. Importantly, everyone's genome is unique, meaning that a correlation between genomes and negative drug reactions must be exceptionally rigorous in order to be believable. Currently, this correlation poses a problem, as our ability to quantify and understand genomes is far ahead of the other dimensions which I mentioned at the start of my post. As our understanding of the microbiome, enteric connectome, and epigenetics increases, it'll be more possible to predict adverse drug reactions beforehand, assuming the patients in question have been profiled.