10 Obscure Gaming Clues That Explained Confusing Moments
7. Why Are Only Girls Used To Collect ADAM? - BioShock
The Confusing Moment
In the original BioShock, it's explained that ADAM - the gene-altering substance present in a species of sea slugs which creates the series' mutagenic Plasmids - is mass-produced by implanting said sea slugs into the stomachs of young orphaned girls, known collectively as Little Sisters.
But why exactly can't young boys be exploited in the same manner? What's so special about girls? Though an audio log discusses this in the first game, no concrete answer is seemingly given.
The Clue
This is actually clarified in the second game's art book Deco Devolution: The Art of BioShock 2, where it's revealed that there were originally plans to fully explain why boys couldn't also be used to harvest ADAM.
The book features concept art for male equivalents to Little Sisters called Little Brothers, though they were only to be featured in the game as failed experiments, as it was their aggression that prevented them from being used to gather ADAM.
And so, it's the unique biology of young girls which makes them best-equipped to yield the most ADAM. Gross, but fascinating.