Does the claim that smoking stunt the growth by 1 inch even true? is there any proof of that or is it just myth created to make teens not smoke?

Smoking: It is true. It is not 100% true, but it is true enough. Smoking leads to lots of carbon monoxide binding to the red blood cells. This leads to less oxygen being carried to the tissues in the blood and thus less healing, less growth, less overall body health. Even in teenagers.

Not true: Smoking causes a host of severe health problems and markedly shortens life expectancy but does not stunt growth.

Hmmmm?: The natural history of nicotine dependence in teens study (funded by the canadian cancer society) published in the journal annals of epidemiology (17 march 2008) showed that on average, teenage boys who smoked were 2.54 cm shorter than their non-smoking counterparts. I have not reviewed this study – so i can not comment on the quality of the research.