Personally, I had an idyllic childhood, then at age 19, had a mental breakdown, with no known cause. It could have been that I was at an out of state college, far away from friends and family, but it was a severe mental breakdown which took years of finding the right medicine. Medicine helped me tremendously.
Everyone is on a unique path, though. I realize some people definitely need to explore their childhoods and talk through things in their life, too. Something I discovered in talk therapy was my aversion to handling life's details. If I had discovered this sooner, I may not have been fired from so many jobs.
Another thing talk therapy helped with, was discovering how deeply I was hurt by the discrimination against my mental illness.
My mental illness was more pronounced, but it didn't appear until I was 19 years old.
Everyone is definitely on a unique path, each of us.
That's the beauty of humanity, the beauty of psychcentral!