Generation 3 synth

Third generation synths are the apex of Institute's research into creating a race of servants necessary to maintain their subterranean habitat.

Background
The most advanced synthetics created by the Institute are fundamentally different from their predecessors, the result of nearly five decades of research, from 2178 to 2227. The research used a sample of the Forced Evolutionary Virus and was intended to produce effective synthetic organics, but it ground to a halt in March 2224, as the research team concluded that the organic synth project could not proceed despite perfecting two FEV strains for the project. Radiation-induced hereditary damage proved too much of an obstacle.

Before developing the first truly organic synths, the Institute would prototype the gen 3 synths as previously proven mechanical synths like generations 1 and 2. The two prototypes were developed distinctly from each other, one testing independent development through experiences (DiMA) and one based on multiple alternating pre-existing personalities derived from pre-War brain scans (Detective Nick Valentine). Each would develop their personalities with promising results but would both escape sometime before the Institute could continue experimenting.

In 2227, the organic synth project was spun off from the FEV research initiative due to the acquisition of Shaun and his undamaged pre-War genetic code. He was recovered by Conrad Kellogg, and his DNA became the basis of the third generation of synths in a project led by Dr. Walter. The infant Shaun became Father to a whole family of engineered synthetic beings. Of course, tests were not without setbacks; in 2229, a defective 3rd generation infiltrator caused the Broken Mask Incident, vilifying the Institute in the eyes of the Commonwealth.

Biology
Despite sequential numbering, third generation synths are unrelated to their mechanical counterparts, but are derived from Shaun's pre-War DNA extensively modified using the Institute's own research into the Forced Evolutionary Virus, combining the advantageous adaptations encoded into FEV with the versatility of the human body shape. This allowed the Institute to create a variety a of synths of varying races and appearances despite the base DNA coming from only one source.

Rather than being manufactured from parts and requiring frequent repair, organic synths are assembled inside the Robotics laboratories from scratch: The skeleton is assembled by giant machines and serves as basis for artificial soft tissues woven on top of it, including analogues for all human components: Brain, lungs, digestive tract, muscles and so on. The unfinished synth's organs are then kickstarted using powerful electric charges and placed in a fluid bath that completes the activation process by rapidly covering the synth in artificial skin. The synth then emerges with the mental faculties of a full-grown adult human. The blank synth is then ushered for processing: Programming and job assignment. Though entirely biological, each Gen 3 synth contains a neurological implant inside their brain allowing them to be "programmed" and manipulated via voice commands. This implant cannot be detected or removed without killing the synth.

The resulting third gens are unlike humans and some liberated synths do not consider themselves human at all. The reasons for this are multiple, chief among them is the assembly process. Other reasons include the fact that synths do not require sleep at all to function properly, are completely immune to disease and don't require the intake of food or water to generate energy for their bodies certainly contribute. Of course, synths are provided with all the requisite components to process food and extract energy from it via digestion and even appreciate taste. All third generation synths share an affinity for Fancy Lads Snack Cakes, mystifying Institute scientists. However, they are physically incapable of gaining or losing weight.

Upgrades
Third generation synths undergo constant upgrades in a manner similar to robots. Where human bodies require careful surgery and complications are common, synthetic organics can be modified extensively without fear of complications. The most experimental upgrades concern their synthetic brains, through the enhancement of specific areas. For example, 2287 saw a major upgrade to synthetic optic nerve tissue for over a thirty synthetics, increasing visual acuity by 10 to 12 percent. Other upgrades the Institute implements in its synths are: The latest models of the third generation display increased autonomous behavior, resulting in a greater number of escapes. Alan Binet, head of Robotics and their chief designer, came under suspicion, leading the SRB to order a full examination of the behavioral mapping in these models, looking for signs of interference.
 * Software package updates, which can provide incremental increases in eg. firing accuracy. The software used by third generation synths may become bugged and require patching.
 * Transfusions, which swap out the entire synthetic blood used in organic synths for superior types that provide improved clotting and infection resistance. Artificial blood strains are identified with codes and the latest upgrade in 2281 switched from blood 77-01 to 90-10.

Identification
Generation 3 synths are physically and mentally indistinguishable from ordinary humans, having lab-grown bodies of real human flesh, bones and organs instead of plastic and metal. As Dr. Roslyn Chambers found, no medical tests or procedures can identify someone as a synth without killing them (synths that infiltrate settlements, for example, only drop synth components when killed). Psychological tests, such as Covenant's SAFE test, are dubious at best. However, they are not perfect duplicates and have a few key differences from humans that are not immediately obvious: synths do not age, nor can they gain or lose weight.

Discrimination
Although synths would qualify as sentient beings for most of the wasteland, the Institute is keen on keeping them under their direct control as servants. The Institute knows that synths are essential to its continued existence, but despite that, the current ideology stipulates that they cannot be granted free will, as it would lead to chaos. The disastrous actions of some synths "liberated" by the Railroad are cited as evidence of that tendency.

Few challenge the ideology and those that do are considered radicals. Robotics head Alan Binet is a noted radical, with his impassioned speeches about artificial sentience and machines a constant feature of Robotics. Binet is keenly aware that his words fall on deaf ears, and when reminded of the option to trade the Institute for the wasteland, he's quick to remark that he's only trying to broaden the horizons of his colleagues. His ideas are unpopular, especially when he suggests they could be the redefinition of humanity. The situation is made worse in the light of the recent increase in autonomous behavior among the latest gen-three models.

Appearances
The synths appear in Fallout 3 and Fallout 4.