Ethically Questionable Achievement
Conduct all of the questionable research experiments.

If you are like me and you don't know what you are doing wrong since you aren't unlocking this achievement, try firing the big laser on the Headcrabs before unplugging the shield.

Just to recap what you need to do to unlock this

Kill the Alien grunt in the chamber with fire, gas or electricity (I am not sure if you need to do all, probably only one will do)
Use the Tesla Discharge on the Bullsquid
Use Poisonous Gas on the Headcrabs in their habitat
Shoot the Headcrabs with a laser, don't unplug the shield IMPORTANT
and last but not least fire the Snark Cannon until it breaks / you run out of Snarks