My mother, my brother and I all have this smell ability to some degree. I remember when I was a child, my mother could diagnose me with strep by smell. (She would also take me to the doctor.)

None of us in the family can tolerate things like fresh paint, dry cleaner establishments, nail polish, and other chemical smells. My mother tended to avoid the "better living through chemistry" cleaning products popular in the 70's and 80's because they bothered her a lot. I, unfortunately, have developed extreme chemical sensitivity, so I'm on the extreme end of this.

FWIW, nobody on this side of my family has ever gotten cancer (knock on wood). I often wonder if our profound awareness of toxins is also protective, in that we completely avoid things that others would be comfortable working with on a daily basis.