2 genetics and mental health studies show no association

Genome-wide association study of recurrent early-onset major depressive
disorder (abstract only) published in 2010
http://www.nature.com/mp/journal/vaop/ncurrent/full/mp2009124a.html
and
No Significant Association of 14 Candidate Genes With Schizophrenia in a
Large European Ancestry Sample: Implications for Psychiatric Genetics
http://ajp.psychiatryonline.org/cgi/reprint/165/4/497

both show no strong genetic factors, at least for common SNPs (single
nucleotide polymorphisms). Schizotaxia and other genetic 'risk' states
may, perhaps, exist over a number of nucleotide sites however i think
that even in that case the sort of method used in the second study
should identify some of the single sites. I really know very, very
little about genetics I'm afraid.

This slightly screws the rational that mental illnesses are part of the
human genetic makeup and an essential part that has been mispathologised.

The effort of psychiatric genetics research is to find this genetic
link. It's important to justify the idea of mental illness as a real
illness. It has little relevance that I can see to treatment unless
treatment is going to be stopping the mentally ill ever being born. It
may help create new medications but I'm not sure about that bit.
Psychiatrists are also interested in the cause of mental illness and
twin studies have shown that there is a significantly increased risk of
a person being schizophrenic if their monozygotic twin is also
schizophrenic.

I'm waiting for the data that shows there is some genetic component
because that supports my view that those that are described as mentally
ill or at risk of becoming mentally ill are just another subtype of homo
sapiens just as those without are are a subtype that, in a different
time or place or a parallel universe could be labelled as the mentally
ill and the same ostensive reasoning applied to their behaviour as an
illness.

The latter study is regarded as the highest quality study at the time
(http://ajp.psychiatryonline.org/cgi/content/full/ajp;165/4/420 - a
critique of the second study). Other studies have shown a genetic link
with common SNPs but none had the size of this study. The conclusion I'm
going to make is environmental factors are far larger than genetic factors.