I think both.
I know and firmly believe that it can be caused by social problems and genetic. My problems were caused by a mother that lost her true love and I was the unwelcomed reminder of that. Through her drinking and all night fighting, she caused me mental problems. Panic attacks, anxiety attacks, PTSS, life long insomnia; these basically creates the inability to communicate with people. Since people did not understand my problems or me, they would become one of two things towards me, either angry or complacent, as if I didn’t exist.
My negative development accelerated through the years, yet no one helped. This indicates that our society at that time knew nothing about child development, nor did it care.
For example, if I had genetically preposition towards math and could do dances around the students concerning math, instead of getting ‘F’s” in all my classes, people would have noticed. In doing so they would have seen the family problems and what it was doing to me and then they would have done something. Why? because society would have deemed my skill useful for society. If people don’t seem to have a value that society appreciates, then there is no real help for a person that starts developing mental problems.
Although society today, seems more displaced than in the fifties, it does have new redeeming values. The child is much more important than in the fifties. Now, a child could get help because society is now attuned to problems of children. Now I would be taken away from the people that were not true parents and I would be tested, helped and moved to foster parents.
If you’re just discussing mental issue in regards to adults that is a different matter, somewhat. With the help children get today and still a certain percentage grows up with mental problems. (This is strongly noted by the deaths caused by young people) It could strongly now lean towards genetic problems, which may be hidden by the parents as the child grows. Some can be cured with medication if the problem can be located. Other types of mental problems can be cured with years of psycho analysis and others will never be cured. There will always be some that will slip through the safety nets our society now have in place. But then again, nothing will ever be perfect because humans will never be perfect.
Hope this helps you a little.