A very interesting submission. If you like long-form videos of scholarly conferences, there is an amazing video of a public presentation by two identical twin sisters who are discordant for schizophrenia.[1] As you can imagine, the sister who didn't have schizophrenia thrived much better in life, and indeed is a psychiatrist.

I am privileged to know Irving Gottesman,[2] one of the world authorities on schizophrenia research (he was the consultant credited by the author of the John Nash biography A Beautiful Mind). He used to be one of the few researchers on the topic who thought that there were genetic influences on schizophrenia, which is now established medical knowledge. In the bad old days of Freudianism, schizophrenia was thought to develop solely from "schizophrenogenic mothers," whose bad parenting caused their children's suffering. It was adoption studies in several countries that conclusively showed that genes matter more than parenting in early childhood in triggering schizophrenia.

And yet environmental factors of various kinds plainly matter too, as the cases of monozygotic ("identical") twins not having identical disease course in schizophrenia make undeniably clear. Gottesman and most other researchers on schizophrenia believe that there are a variety of genetic vulnerabilities that people may or may not have that increase risk for schizophrenia, and then stressors in the environment (and it is not excluded that some of those stressors may be purely psychological, influenced by interactions with other people) trigger the expression of full schizophrenia symptoms. This is called the diathesis-stress model of schizophrenia, and the same model is believed to a helpful research hypothesis for study of depression and suicide.[3] So if you know someone who suffers from schizophrenia, the compassionate thing to do is to help the person find current medical treatment (which has improved enormously over the course of my adult life) and to cope with day-by-day life stresses.

EDIT ADDED AFTER AN HOUR:

Several other comments here involve participants who have close family members with related diseases, or who have related diseases themselves. That's rough. I hope Hacker News is always a compassionate community where you can share your experiences and then encounter empathy and helpful advice. We should support one another here.

[1] Video hosted on YouTube:

https://www.youtube.com/watch?v=lzDPlktZrGI

Transcript of presentation:

http://www.virginia.edu/uvanewsmakers/newsmakers/spiro.html

[2] http://www.psych.umn.edu/people/facultyprofile.php?UID=gotte...

[3] http://www.ncbi.nlm.nih.gov/books/NBK107203/