BIOGRAPHY - PAGE 1
Whilst it would be easy to assume that the identical appearance of the Stepford Cuckoos was a part of their mutation, the actual truth is even more bizarre. Many years ago, Emma Frost led her own team of teenage students called the Hellions, who were tragically killed in a horrific 
battle. During the fight, Emma was blasted by a Sentinel and the damage was so severe she remained in a coma for many months.
Unbeknownst to her, whilst she was asleep, a man called John Sublime from the Weapon Plus program harvested some of her eggs to use in his own nefarious plan. Using the eggs, Sublime created over a thousand identical, female embryos, all of which had telepathic powers like their mother, as well as highly sophisticated nano-technology within their cells. Naming the project “Weapon XIV,” he utilized the time manipulating technology of The World and placed the embryos in stasis tubes to grow them at an accelerated rate. While only a few years passed outside "The World," inside enough time went by for the embryos to develop into teenagers. Sublime’s ultimate goal was the eradication of the mutant race and he intended to use the combined forces of the telepathic girls to kill every mutant on the planet. Individually, each girl was a gifted psychic, but together they formed a powerful hive mind that would rival even Xavier himself.
Before he could unleash his endgame, though, he needed the girls to train their fledgling telepathic talents. He determined the best way to do that was to send them to the X-Men to learn, whilst having the added benefit of sending data on the mutant team back to him. He woke up five of the girls and gave them identities with which to enroll at the Xavier School. With that, Sophie, Phoebe, Irma, Celeste and Esme were “born,” dubbed the Five-in-One and sent off to gather the information required. Not only were the girls themselves unaware of their true origin and purpose, to stop anyone questioning their history they emitted a psychic deflection making everyone accept their stories and appearance at the school without question. [X-Men: Phoenix -- Warsong #1-5]
Fortunately for them, the Xavier Institute had opened its doors up again and numerous students were enrolling at the school, allowing the Cuckoos to slip in without much drama. By pure coincidence, Emma Frost, who had woken up from her coma years before, was now a teacher at the school and also operating as one of the X-Men. While neither Emma or the Cuckoos were aware of 
their family ties, they seemed to gravitate towards one another, probably due to their very similar powers and demeanor.
Since the five girls had a telepathic hive mind, they became used to operating as one unit, often speaking together and rarely interacting with others on an individual basis. The Cuckoos did not make many friends at the school, due to their cold, almost condescending attitude. Regardless of their closeness, though, the girls slowly started developing their own personalities and traits, with Esme becoming the more headstrong and rebellious of the group. She was the first to show an interest in one of the male students, Kato, much to the chagrin of the other four girls. The rest of the Cuckoos did not trust Kato, and they were proved right in their feelings when he turned out to be the alien shapeshifter Stuff, sent to infiltrate the school.
After having her heart broken by Stuff, Esme rejoined her sisters and helped them psychically attack some of the Imperial Guard when the Shi’ar attacked the school. Whilst the majority of the Guard were distracted with the main X-Men team, the Stepford Cuckoos teamed up with Angel Salvadore to aid in the best way they could. The Guard were at the school because Cassandra Nova was manipulating them, so the Cuckoos devised a way to contain Nova. The girls were able to exact revenge on Stuff by using his body to trick Nova into inhabiting it, trapping the evil telepath in there permanently. [New X-Men (1st series) #118-126]
Despite their antisocial attitude towards their other classmates, Sophie somehow earned the admiration of fellow student and telepath, Quentin Quire. Unfortunately for him, she did not like him one bit and made her feelings known to him loud and clear. Quire had been through a turbulent few weeks and Sophie’s dismissal of him did not help one bit. The Cuckoos warned the teaching staff that Quire was unstable and was likely to try something disruptive on the school’s open day, but their warnings went ignored. Sure enough, Quire started a riot at the school and things turned violent very quickly, with Xavier being held hostage.
Sophie led the Cuckoos to Cerebro, where she intended on using it to boost their brain power in 
the hopes of stopping Quire. For a change, it was Esme who was the one warning her not to do anything dangerous, but Sophie ignored her and took a dose of a power-increasing drug called Kick, and began to operate Cerebro. Together, the Cuckoos attacked Quire psychically and put an end to his schemes, leaving him nothing more than a blabbering mess on the floor. Unfortunately, the use of the drug and Cerebro combined took its toll on Sophie and she died before anyone could help her. The other Cuckoos, now the Four-in-One, were devastated at losing one of their own and they turned on Emma Frost, blaming her for inspiring Sophie to be a superhero. In a vicious putdown of their mentor, the girls told Emma they were leaving the Institute. As a final shot before they left, they informed Jean Grey that Emma was having a psychic affair with her husband Cyclops. [New X-Men (1st series) #134-138]
Naturally there was a fight between Emma and Jean over the recent revelation and the Cuckoos watched in delight as Emma got her comeuppance. However, before they could leave the Institute for good, Emma Frost was mysteriously killed by someone and the entire school was placed on lockdown until the culprit could be found. Naturally, Bishop and Sage, who were investigating the crime, wanted to speak to the Cuckoos given the recent history between them, but they claimed 
to be at the opera with Beast at the time of the murder. Their alibi quickly started to unravel though and Esme decided it was time to leave the Institute regardless of what was going on. She was stopped by Bishop before she could leave the grounds and he confronted her, revealing he knew she was the one behind Emma’s murder. Sage arrived and helped fill in the gaps by informing him that Esme had been using the drug Kick for a while now to boost her own mental powers so she could manipulate the rest of her sisters. When Sophie resisted, Esme orchestrated things so that her sister would be killed, removing the obstacle. She then took control of Angel Salvadore and used the girl to shoot Emma Frost, shattering her diamond form. The two investigators didn’t understand why Esme had done it all but they theorized that she was actually working for someone else. Esme refused to tell them who she was planning on meeting; instead she psychically attacked them and left the Institute before anyone else could stop her. [New X-Men (1st series) #139-141]
The other Cuckoos were angry at being used by their sister and formally denounced her, whilst 
declaring they were now the Three-in-One. They didn’t have to wait too long to discover who Esme had secretly been collaborating with, as the X-Men’s newest teacher Xorn was revealed to be Magneto in disguise. Taking the opportunity to strike whilst the X-Men were otherwise engaged, Magneto created a new Brotherhood around him and destroyed much of New York City. Esme was rather enamored with Magneto, remaining his most loyal team member and even chastised the others when they fell out of line. Still using the drug Kick, Esme managed to convince Magneto that he should also take it to amplify his powers to devastating effects. The humans of the city were rounded up thanks to Esme pacifying them with her powers and her mean streak started to show through as she delighted in punishing them.
Unfortunately, her confidence in the belief that she was Magneto’s most trusted follower started to 
grate on the others and even Magneto himself, who was beginning to get irritated by the young girl. When she professed her love for him, Magneto finally snapped and told Esme that she was only a child and he used her as a means to an end. Devastated by the revelation, she immediately turned on Magneto and taunted him as his plans for world domination started to fall apart. Elsewhere, as the destruction of the city raged on, the Three-in-One banded together with a group of students to oppose Magneto. With electromagnetic devices down, the Cuckoos were the only way of communicating with the rest of the X-Men.
When the X-Men attacked Magneto and destroyed his helmet, Esme snatched her chance to 
exact revenge on him and slowly induced the effects of Alzheimer’s in his brain. Her arrogance became her downfall though, as she waited too long to kill him, giving him the opportunity to rip her metal earrings out and push them into her brain. As she lay dying on the floor, she was discovered by Emma Frost, who had been brought back to life after Esme left the Institute. Instead of seeking vengeance, though, Emma held the dying girl and proclaimed she was proud of Esme the most. Magneto was eventually killed but not before killing Jean Grey out of spite. [New X-Men (1st series) #146-150]