Moira was born the daughter of Lord and Lady Kinross, old money nobility from a bygone age and thus the owners of a vast wealth and heritage. Even as a young schoolgirl, she found a natural inclination and knack for how things worked, finding a wide variety of sciences fascinating and challenging. Moira decided at an early age to become a doctor and through stellar grades, hard work and a little help from influential parents, she found her place at the prestigious Cambridge University in England.
It was there she fell in love with Charles Xavier, an American graduate student following the field of genetics. Looking back, Moira would say she knew just by laying eyes on him he was destined for great things and found herself attracted to his intelligence, determination and passion for his work, not to mention his more subtle charms. They found similar interests, the same ideals and soon, the same love. They took many trips together, shared many moments and she promised to be his bride. She even took up his particular study interests and found a great deal to be learned and discovered in the field of genetics and human mutation. This interest soon became a life's obsession, earning Moira a Nobel Prize for her work in isolating the 'X-Factor' gene, said to cause active mutations in Homo sapiens.
When Xavier was called to war, she waited, but another man came into her life: Joe MacTaggart. A seemingly sweet and gentle man, he became quite rough with her as she dissuaded his advances. After all, she was waiting for Charles... wasn't she? After an unknown turn of events, maybe threats, maybe pressure on her research work (the MacTaggart family had great political ties and could easily squash her grants), she unexpectedly wrote a brisk and distant letter to Charles, cutting her ties to him and breaking off their engagement. A difficult letter that became even more painful to her as the whirlwind romance of Joe MacTaggart came to a crashing halt. After winning her Nobel, he became more self-possessed, arrogant and abusive, slowly becoming a nightmare to live with.
It was a horrible marriage, one she eventually fled from, divorcing him quickly while still pregnant with their child and taking up residence on her family estate on Muir Island. By that time, the Island was home to the burgeoning Biology Institute and Medical Facility she had been building after the success of her work and the acceptance from the European Medical community and was able to give birth to her first son there in a protected environment, unfortunately needed. Kevin was born with active mutant abilities that were so strong his body was not able to contain the enormous energy burgeoning inside of him. Moira had to lock him in a pressurized cell to avoid his death, and dove into her work in an attempt to save her son. Eventually, she contacted Xavier, doing her best to patch things up between the two of them for a united effort.
As she called upon him in times of need, Xavier began to ask the same of her; with the formation of his X-Men, Moira MacTaggart was enlisted as a medical advisor and de-facto 'school nurse', providing assistance as needed to the school. From providing a place for those with more high-risk mutations to learn control and acceptance in a safe environment to simply providing a tremendous opportunity for those students interest in science to learn from a Nobel winner, Moira begun to split her time between the international scientific community and the Xavier Institute.