Oh give me a freakin break!
All my uncles and aunts were raised in a house heated with coal and they were all at least 6’ 3”.....
Think of how tall they would have been if they’d burned wood!
Aha! See??!! They could have been at least 6' 3.5" had they not used coal!
I'll call this a load of BS. They already have ready made test and control groups. Why go through this?
East Germany, and I'm sure most of the Warsaw Pact used to burn soft, brown coal. You could walk the streets of East Berlin and they would just pile it up on the corners in front of the buildings.
This crap was so bad that in the winter when the winds were still or fog enveloped the city walking around East Berlin would fill your nose with black, crusty boogers. Imagine living like that.
Anyhow, point is look at folks born in 1970 in East Germany and compare them to folks born after reunification when the enormous amounts of pollution left by the Communists were cleaned up.
But sans the coal they might have been 6’ 3 1/2”, LOL.