I had a client who came to me for anxiety: it turned out to be second hand anxiety. The cause of her anxiety is direct result of her upbringing, which was a direct result of events.
Her father was Polish, and was conscripted into the army early in WWII. His unit was captured by the Germans. He was imprisoned in a labour camp. Thousands died through brutality, starvation and disease.
The Russians over ran the camp but instead of liberating them all, he was conscripted into their tank battalion. As part of that battalion he endured the horrors of fighting on the Eastern Front right up to the end. Eventually they let him go due to pneumonia.
The result of his privations and captivity was that he had lung disease for the rest of his life. He also had survivors' guilt, night terrors and PTSD. So she was brought up in a household where her father was constantly in and out of hospital, he was often absent or lying sick in his room, there was never enough money, and constant worry about the future.
My client had a lifetime of caring for him, not having a real dad, and not having a settled home life. She became anxious and constantly stressed. Most likely this triggered her own life long anxiety. It also led to her becoming a professional nurse.
What is notable about all this is that my client is in her late sixties, and still suffering from something that happened in the 1930's, long before she was born. The evils of the second world war are still with us today.
It is quite remarkable how long historical events can reach into daily life. And if my client's children are in turn affected by her behavior then they, in their old age, will still be suffering for what happened over a century before.