That brings up an interesting point. In my youth (1950s) I was taught to care for the less fortunate and to be against discrimination by government. I was a Democrat. By the time I was 40 my attitude about those things hadn't changed. But my view was (still is) that much smaller government was the way to accomplish those goals. i.e. a libertarian attitude. (not to be confused with a Libertarian attitude). My kids seem to have started out with my libertarian attitude: http://classicalvalues.com/2012/06/a-rally-report/

kjmtchl, From what I have seen re: PTSD studies and twin data, heritability is given as 50%. But that is not in fact the case. We know from general population genetic studies that about 20% of a population is susceptible to PTSD and yet only 1/2 those are affected. OTOH in high stress war zones reports of the % of troops affected runs in the 20 to 25% range. About what you would expect if 100% of the susceptible get enough stress. Twin studies do not in fact control for environment. As far as I can tell. I'm sure it can be done (or done better), but that is currently not the case. IMO. I only know this because the study of PTSD is a hobby of mine. So I'm not deeply conversant with the general field of genetics and heritability.

I have skimmed the comments (I may have missed something), but what if a trait only manifests when given certain environmental triggers (we know that is true for PTSD - it is in the name)? If a certain population has a gene and yet only 1/2 get the trigger then right away heritability is down to 50%. Is that really the right way to look at all this? Some have noted that all the complexities of genetic interactions have not yet been teased out. Throw in the environment and there are a LOT more threads to untangle.

The argument for libertarianism is much simpler: since people vary (for what ever reason) a minimum of one size fits all rules is the best way for each individual to take maximum advantage of the gifts s/he is given. Take our rules on LSD - some people can profit greatly from it (Steve Jobs), others are debilitated by it. Should Jobs (and others) be denied the profits (which are societal as well as personal) in order to putatively save those that can't handle it? And of course in a prohibition regime no one is saved because distribution is handled by criminals and they don't check IDs or check your psychology. They just check the cash.

You asked in another post with comments now closed to look at untouchable questions. 
 
Here is one. 
 
1. We "know" that "addiction" is heritable. (only about 20% of the population - in America - is subject to the "malady"). 
 
2. We "know" that it is subject to environmental influences. Only about 50% of the susceptible population is "addicted". 
 
3. We label some addictions (insulin) as adaptive and others (heroin) as maladaptive.  
 
Might not our war on "addicts" be a war on those trying to adapt based on their genetics and circumstances? i.e. it is bigoted. Mine might be called the endorphin deficiency theory of addiction. Or in milder cases the CB1 deficiency (cannabis to the rescue) theory of addiction. Or in the case of ADD/ADHD the stimulant deficiency theory of addiction. 
 
In addition the NIDA supports the genetic theory of addiction plus "something else". I have pretty good evidence that that "something else" is trauma. 
 
So not only are we punishing people for their genetics, we are in fact persecuting the traumatized.  
 
I have been trying to get people to look at this for at least 6 years. Even with the NIDA's statement on the genetic aspects of the question, it is near impossible to get people interested in these questions. 
 
It depresses me. I think I'll have a cigar and a bottle of beer. (Tobacco is an anti-depressant favored by schizophrenics). 
 
Just as the IQ arguments re: race are untouchable questions so is the question of the nature of addiction. 
 
BTW I'm a little late for Merry Christmas so: 
 
Happy New Year.

The harder the subject is to understand the more women admire it. 
 
Biology? Had that in high school. 
 
Genetics? Well that conjures up statistics, math, chemistry (which is harder than biology). etc. 
 
Thus genenticists have more brains than biologists.