My aunt ( my father's sister ) had restless leg syndrome. My mother had severe migraines and intermittent depression. So only a hint of genetic influence, but:
My whole family smoked - I was the only non-smoker - I grew up in pollution.

There has always been pollution of a kind, especially to people with allergies:
Coal dust, coal smoke.
Wood smoke from fire places and open fires.
Pollen, dust, animal dander.
Wet lath, tar, paint, mold, damp.
Food poisoning.
Etc. etc. etc.