John White

John White was a whitecoat working for the school. He was the husband of Opal White, and father of Kathrine White and Ellen Alberich. It can be concluded that he had his affair with Taika Alberich after his marriage, due to the age difference between Kat and Ellen.

Skills
It is presumable that he was skilled in creating mutants, as he mutated his daughter, Ellen, and knew there was a chance of a disease, caused by a genetic disorder, being given to her. Of course, this didn't stop him from 'preparing her for the new world.'

We can guess he specialized in genetics and creating mutants.

(See Jopal)
John married Opal, and she is the mother of his firstborn, Kathrine. Opal also seems to have genetic knowledge, which may imply they met at school or in the School. He cheated on her with Taika, at some time after their marriage.

(See Joika)
John's lover, Taika mothered John's second child, Ellen. He probably loved her more than he did Opal, as he did cheat on the latter with the former.

Kat and Ellen
John's relationships with his daughters are vastly different. Kat loved her father, mourning his death after the fire and fearing her powers somewhat because of it.

Ellen, on the other hand, did not love or even like her father. When Taika brought him to meet her, Ellen tells us in her diary that "I told him to burn in hell." Ellen herself made the fire kill him, though she didn't know it. John did mutate Ellen, though.

It is possible he had more affection for Ellen than for Kat, as he didn't 'prepare' Kat as he did Ellen. He may have been planning to, however, or perhaps the mutating of Ellen shows a lack of love for Ellen, favoring Kat. Sage will let you think on that yourselves.

Trivia

 * He is the half-brother of Alfred and Maria Drevis.