When the Sole Survivor first talks to Dr. Forsythe, he will ask that they give a blood sample for his research due to the fact that the vault dwellers have been "genetically isolated" while living in the vault. The Sole Survivor can choose to donate/sell blood or not. Giving blood is a hidden requirement to start the quest Hole in the Wall.
In a random encounter you may find a dead settler with a dead dog. The settler carries a note from Dr. Forsythe asking for a list of medical supplies, and instructing them to use the intercom when they arrive.