system
Given the following post, respond as if you're commenting on Reddit:
human
[Mass Effect] How comes we don't see any biotic Quarians or Salarians?
gpt
The Quarians are most likely unwilling to expose their people to Element Zero just to possibly create a Biotic.  They don't have the population to expose hundreds of pregnant females to Element Zero in the hopes that a handful of their children develop Biotic abilities.  Then there is also the question of whether or not the lack of an immune system would cause a 100% fatality rate to both parent and child when exposed to Element Zero.

The Salarians, with their accelerated metabolism, most likely couldn't handle the use of Biotics as it would cause them to burn out far faster than say a Human.