As a boomer, I say "baloney".
For starters, my dad grew up in the Depression. His schoolmates called them "coffin nails". Doctors routinely prescribed "stop smoking, you fool".
In 7th grade, one of my teachers (incidentally, a Holocaust survivor), smoked constantly. He'd also spend half of class time coughing up a lung. My best friend in high school smoked constantly, and told him his doctor told him his lungs were damaged and he better quit. He kept smoking.
But the worst was when I was 8, and toured an agricultural museum at K State. There were two jars with lungs in them, one from a non-smoker, and the other a smoker. The non-smoker lungs were pink and looked healthy. The smokers - black! All black! It was horrific.
Besides, anyone who cut open a dead body knew instantly if the deceased was a smoker. No sane person would conclude the black, scarred lung was healthy.
All the boomers knew the bad effects of smoking. They just thought they were invulnerable.