One of the biggest hot button issues of all time has to be eugenics. In a nutshell, eugenics is the idea that humans should practice selective reproduction in an effort to “improve” the species.
Tara Rodden Robinson, Genetics for Dummies, Wiley, 2005.
hot button noun [C] US SLANG
a subject that is important to people and which they feel strongly about:
Gender issues have become something of a hot button.
Abortion has become a hot button issue. [CALD]