>>528054018
people who arent affected by caffeine have a gene variance of DRD2 and/or COMT; the former being directly related to how well caffeine blocks adenosine, which in turn produces dopamine; while COMT has to do with how well your liver metabolizes caffeine in the first place and therefore feels any effect at all; 40-50% of the population globally have these two genetic variations.

prescriptions can directly alter the gene expression to that of someone who is better suited for caffeine