Les Enfants Terribles

Les Enfants Terribles (The Terrible Children), was a United States Government project developed in the early 1970s, which aimed to produce clones of the legendary soldier Big Boss. The project was sponsored by Zero, the central figure in the Patriots organization, and was carried out by Dr. Clark. The name of the project was presumably inspired by the novel and the 1950s film of the same name.

For more info on the history of the project see here.

The Twin Snakes
The initial phase of the project involved manipulation of Big Boss' genes to create genetically identical clones. An egg from Dr. Clark's Japanese assistant was fertilized with Big Boss's DNA and transferred to the womb of EVA, another member of the Patriots, who acted as a surrogate mother. This success was the result of multiple attempts, with the project only having borne fruit after dozens of failures. Of the eight embryos created from the fertilized egg, six were intentionally aborted, thus producing twin clones. Further work was done so that one clone would express each of Big Boss's dominant soldier genes, which was intended to create a genetically superior soldier, while the other would express his recessive genes, which were considered inferior for the project's goals. Because of the respective gene expressions, the twins had a genetic difference of .43% The Patriots intended that the clones be used as a future insurance policy should Big Boss choose to directly oppose them. Jim Houseman also heard of this phase of the project, and expressed distaste for it thirty-three years later.

The clone with the superior soldier genes became known as Liquid Snake, and the clone with the inferior soldier genes known as Solid Snake, although Liquid was led to believe that the reverse was true. As a result of Big Boss's perceived influence, Liquid believed that he was the inferior of the original twin clones. When the two met for the first time as adults, Liquid refered to them as the "Brother of Light" and the "Brother of Dark." He did not acknowledge any given name and reacted angrily to Solid Snake's claim of having one himself. In spite of his supposed genetic shortcomings, it was Solid Snake who defeated both Big Boss and Liquid Snake.

Despite being clones of Big Boss, both Solid Snake and Liquid Snake did possess some East Asian DNA in their genomes, as a result of the Les Enfants Terribles project. The donor egg, provided by Dr. Clark's Japanese assistant, passed on mitochondrial DNA to the clones, though their nuclear DNA was still entirely composed of Big Boss's genes.

Zero briefly discussed the Twin Snakes with Kazuhira Miller in late 1974, after the latter asked about news on the "sons."

The Third Son
The creation of the original clones was the last straw for Big Boss, who left the Patriots in disgust. As a result, Zero required a perfect clone of Big Boss to act as a replacement of Big Boss, and later to provide the DNA-based key to access the master AI. Thus Solidus Snake (meaning neither solid nor liquid) was created to be an exact clone of Big Boss, without any modifications to gene expression. The egg donor and surrogate mother used in this phase of the project are unknown. Solidus was later known as George Sears, and the Patriots also intended to use him as a puppet ruler for the country, and arranged for him to become President of the United States. However, he, like his father before him, eventually revolted after he realized that they were just using him like a pawn, and then was forced into resigning and went into hiding.

Accelerated aging and sterility
Each clone had accelerated aging (or Werner Syndrome) written into their genes in order to provide a fail-safe against the clones falling into enemy hands, or if the clones turned against the Patriots under their own volition. In Solidus's case, this aging was apparently faster, thus providing the figurehead that the Patriots required (a U.S. President in the image of Big Boss) in a relatively short amount of time.

All three clones also lacked the ability to reproduce, which according to Solidus, had been "conveniently" written into the clones' DNA. It is this that drove Solidus to leave behind a lasting legacy to the world, due to his forthcoming death from advanced aging. Also all three clones had terminator genes so that they can not be cloned.

Abilities
Because of the nature of their conception and development, the Les Enfants Terribles children possessed enhanced natural abilities and durability, surviving and withstanding physical and mental situations that would result in an average human's death or mental breaking. In addition, Ocelot implied that the Les Enfant Terribles project also resulted in the children having a heightened and natural aptitude with piloting vehicles.

FOXHOUND codenames
When David joined FOXHOUND, he was assigned the codename "Solid Snake." Since Big Boss was in charge of the unit at the time, he may have awarded him the codename in reference to his old FOX codename, Naked Snake. Another possibility is that the codename was part of the FOXHOUND ranking system in use at the time, where in "Snake" may have represented soldiers with a skill level similar to Big Boss during his time with the FOX unit. A FOXHOUND codename also contained a personal prefix to distinguish between those with the same codename, thus David's clone designation of "Solid" was used. It is unclear why this was used or which individuals knew the meaning behind the designation.

Later, when Liquid joined FOXHOUND, he was awarded the codename "Liquid Snake." It is unclear if the ranking system was still in place (wherein his abilities would assumedly award him the same codename as his brother) or if Liquid chose the codename himself as the other members of FOXHOUND did at that time (he may have already been aware of his relationship to Solid Snake at this time).

Having never been a member of FOXHOUND, President George Sears was referred to as "Solidus Snake." However, he did at one point pose as Solid Snake, and the codename is seen as appropriate considering his lineage.

Trivia

 * As Elisa and Ursula died during the San Hieronymo Takeover, she had a precognitive vision of Naked Snake's future: that Big Boss would build his own Metal Gear, one of his sons would bring the world to ruin, and another of his sons would save it. During this state, she explicitly used the phrase "Les Enfants Terribles."
 * During Liquid Ocelot's Insurrection, Philanthropy had three chickens that were named after the Les Enfants Terribles children.

Behind the scenes
The name Les Enfants Terribles was earlier used for a minor French terrorist group, mentioned in the MSX2 version of Metal Gear 2: Solid Snake, of which the mercenary Running Man had originally been a member. The group is not mentioned by name in the PlayStation 2 version included in Metal Gear Solid 3: Subsistence, most likely to avoid any confusion. The Metal Gear Solid 4 Database, implies that the name of both the project and the terrorist group were inspired by Jean Cocteau's Les Enfants Terribles. In the English versions of both Metal Gear Solid and The Twin Snakes, it was stated that Big Boss was in a coma when they commenced the project. However, the Japanese version of the former game only mentioned that he ended up sterile.

In the non-canon game Metal Gear: Ghost Babel, Solid Snake tells Chris Jenner (in an optional Codec conversation) that Big Boss was his father, but he does not elaborate on whether it was due to the Les Enfants Terribles project.

Metal Gear Solid 2: Sons of Liberty was the first game to reveal that the clones of Les Enfants Terribles age at an acceleated rate, given Liquid Ocelot's comments to Solid Snake aboard the U.S.S. Discovery, and Solidus Snake's advanced age.

Three types of snake can be located in Metal Gear Solid 3: Snake Eater, during the fight against The Boss in Rokovoj Bereg. The three individual snakes are called Liquid, Solid, and Solidus. Their skin complexion and eye color suggests that the three snakes are albinos.

In Super Smash Bros. Brawl, when Snake fights another player also using Snake, the player can initiate a Codec conversation with Colonel Campbell, who starts wondering, "Has the Les Enfants Terribles project really come this far?" Snake explains that his doppelganger has more than physical and genetic appearances that make them alike, it is also the fact that he has his fighting style as well, although it's not exact.

In the novelization of Metal Gear Solid, President Nixon asks if the birth of the Twin Snakes is the ninth attempt, to which Dr. Clark confirms, revealing that eight previous attempts had been failures until the genetic batch was corrected.