Quit smoking not just for yourself but for your children.
Studies have repeatedly linked maternal smoking during pregnancy with reduced sperm counts in male offspring. Now a research team at Lund University in Sweden has discovered that, independently of nicotine exposure from the mother, men whose fathers smoked at the time of pregnancy had half as many sperm as those with non-smoking fathers. [emphasis mine]
Possibly applicable to vaping as well!
Parents who want great-grandchildren (and who want their kids to have grandkids) might try harder to dissuade their teens from starting smoking and vaping, if they know about these results.