In order to do this, you
must RESCUE all the little sisters in the game. This will give you
As well, you
MUST NOT KILL 3 people that you are given the option to kill during the game. These include
1. Grace, whom you meet at the end of Paupers Drop. You'll meet her at the end when you infiltrate her hideout full of splicers. When you find her in her secret place, she'll open her door and you have the option to kill her. Don't hurt her and just get the item and leave the room. The door will close and she will start saying stuff to you through the radio.
2. Stanley, whom you will meet at Dionysus Park early in a locked train room. You have to complete a few tasks before the door unlocks. Then when your going back to the train at the end, Lamb will open the door so you can decide his fate. Just go in the room and pick up items if needed but don't hurt him and just go in the train and leave.
3. Gil at Fontaines Futuristics. At the end you get to a dark lab with a huge tank. Gil wants you to find plasmid plants before you can decide Gil's fate. After collecting, you put the adam in the tube. After, Gil will tell you to kill what's inside, and there will be a switch that flashes
Don't press it, just leave the lab and go to Lamb's hideout. After reaching the hideout, the achievement unlocks.