Friday, April 16, 2021

Comments by CMiller225

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  • Everything that has to do with phenotype, whether it’s susceptibility to disease, physical appearance or mental health, is a result of genes interacting with the environment. Think about it. If we had the genes of a mouse, our behavior would be very different; alternatively, if we were raised on Mars, our behavior would be very different from Earthly counterparts. A good example of how genes and environment affect behavioral outcome is the response of some individuals to marijuana use. Whether it is studies of siblings in Australia (McGrath et al.) or twins in Sweden (Kendler et al.), the young person using marijuana is more likely to develop psychosis, yet not all individuals worldwide suffer this risk. (about 5% of those who use potent marijuana heavily could be expected to develop a psychotic disorder; DiForti et al.). What this means is that both environment (in this case, marijuana use – McGrath et al. and Kendler et al.) and innate differences between individuals (DiForti et al.) make a difference. We just don’t know what genes make a difference for each environmental variable, and the PRS scores were researchers best attempt to put together a set of genes that could account for all environmental forces of importance, but they failed to develop a set that applied to enough people to be meaningful. With marijuana as the environmental variable, there will undoubtedly be genes of risk that are specific to THC metabolism and THC receptors, and not all those genes are well characterized at this point in time and were unlikely to be part of the PRS scores for behavioral disorders.

    What must be done is to set up a PRS score for each environmental component thought to increase risk for a particular behavioral disorder, and then we might get somewhere. But to say that genes aren’t important in behavior because the set of genes chosen for the PRS analysis weren’t correct, is ridiculous. Anyone who maintains that genes have no role in behavior is ignoring the differences in behavior that clearly exist between other species and humans, and those differences have nothing to do with environment.