Stephen Strange was born to Eugene and Beverly Strange in 1930 while the couple was vacationing in Philadelphia. In 1932 Stephen's sister Donna was born at the family's Nebraska farm. Knowing that Strange was destined to become the next Sorcerer Supreme, a resentful apprentice sorcerer Karl Mordo beset the child with demons from the age of eight through to adulthood, as he was jealous that a kid would be better than him. Ultimately Strange was rescued by Mordo's master, the Ancient One, mystic protector of the Earth-realm as the current Sorcerer Supreme. A year or two after this torment began, Stephen's brother, Victor, was born. At age eleven Strange aided an injured Donna, an experience which ultimately fostered an interest in medicine. Strange entered New York College as a pre-med directly out of high school. Later, while home on vacation for his nineteenth birthday, Strange was swimming with Donna when she suffered a cramp. After a frantic search Stephen found her already drowned. The experience left him with a sense of personal failure that eroded his medical idealism.

(Source: Marvel Database)