The Genophage was a horrific biological weapon used by the Salarians to control the Krogan population in the world of Mass Effect. When deployed by the Turians, who got their hands on it, the genophage caused only one out of every thousand Krogan births to be successful. This succeeded in virtually annihilating the Krogan population and wreaking havoc on the warlike species.
In Mass Effect 3 (spoilers ahead, you're warned), you are brought headlong into the ongoing genophage crisis and given a choice; cure the genophage and bring the miracle of life back to the Krogan race or don't cure it and essentially say, 'screw this entire race of sentient beings!'. 8% of Mass Effect 3 players chose to not cure the genophage, instead leaving the Krogan race to their Turian-induced inability to reproduce.
What is wrong with you guys? Like, seriously.
This factoid is but one of dozens released at BioWare's Mass Effect Retrospective panel from PAX East 2013 in Boston, MA. The full infographic can be found below and it is a fascinating way to kill five minutes.
Check it out (click to enlarge):