So im studying population genetics right know in my ecology class, and I learned of a technique called regresional analysis to see to what extent a phenotype is heritable. I found it fascinating that there is the possiblity of a phenotype being mediated almost entirely by the enviroment. That said phenotype would not be heritable. Being interested in psyhchiatry I started to think of how this could apply to psyhchiatry.
I was wondering if there have been any studies using regresional analysis to see to what extent psychiatric disorders are heritable.
*calms down*
I thought you were talking about past-life regression therapy for a second there.
Regressional analysis is a basic statistical technique used in all fields to figure out the relative contribution of one variable to the variance in another.
Any time you read about 'heritability' of any trait you are reading a regression study about this. There is lots of work out there in psychiatry and medicine in general.
But there are a lot of problems with trying to study a population with significant developmental plasticity, as well as life histories and behavioral ecologies vastly different from the environments in which they evolved.
I'll expand briefly on that before I run off. Take for example type II diabetes. Most studies will say that hispanics, asians, and blacks are more predisposed to diabetes than white people. However, if you study those populations in the US, eating like Americans/Europeans, you are studying a population not behaving in accordance with the conditions in which their genes arose. It's true that if these populations eat like westerners, they are more predisposed to diabetes. If they eat more in accordance with their own traditional diets, they aren't. In fact, some researchers have implicated the mechanisms behind increased risk of developing insulin resistance in certain ethnicities to their ability to build muscle faster with less protein than whites.
The main thing is that the gene is a meaningless entity in and of itself. It tells you nothing. Nature selects for physical traits. Physical traits are determined by both gene and environment. So what we should be studying is the gene-environment pair. That's the lowest reducible level of understanding for any gene with any degree of phenotypic variability due to environment. And everything is context dependent. The same genes that make kenyans such excellent runners are the ones that make them poor weight lifters. The same ones that make whites famine resistant are the same ones taht make it harder for them to lose weight in many cases.
In something as adaptible and plastic as the brain, I suspect that the gene-environment pairing and context are far more important than the gene itself.
