In BioShock, just 27% of global Xbox 360 players with the game managed to unlock the Little Sister Savior achievement, which is awarded for completing the game without harvesting any of the Little Sisters. This means, when presented with the option, 73% of players decided to kill the sweet darlings without mercy
If I remember correctly, I only killed one accidentally when the button prompts for two different actions overlapped at the worst possible time, costing me the achievement in the process.