Here goes nothing.
Magneto married a woman named Magda, who, upon discovering he was the Mutant Master of Magnetism (TM), runs away from her husband into the mountains while she is pregnant with her two twins, a boy and a girl, and collapses in the mountains, conveniently on the door step of the High Evolutionary, who changes animals into bipedal human like beings as a hobby. Magda gives birth to Wanda and Pietro and dies. They are raised by their cow mama Bova, until it's decided that Wungadore is no place for human children.
Wanda and Pietro go off to live the gypsy lifestyle. They demonstrate mutant powers, and are recruited ironically by their own father for the Brotherhood of Evil Mutants. Neither children nor father know of their relationships.
Magneto treats everyone in the Brotherhood of Evil Mutants mean, thus giving credence to the word evil. Battles with the X-Men ensue, and neither twin feels good about being in a group that has evil in the title, but they stick anyway. But Magneto is kidnapped (along with the Toad) and Wanda and Pietro are suddenly free.
So, Wanda becomes Hawkeye's friend, the Avengers are going through a rough patch, and Cap puts together a second generation of the Avengers team that's sort of like an informal superhero probation squad. All of the ex-cons make good, saving the planet and stuff like that, and Wanda Maximoff becomes a super heroine.
With me so far?
Mirrored from Writer Tamago.