Greg Mortenson was born in Minnesota in 1957, but he grew up in Tanzania, Africa. His father was a missionary who founded the Kilimanjaro Christian Medical Center in Tanzania, which is a teaching hospital. His mother founded International School Moshi on Mount Kilimanjaro, Africa's highest mountain. Perhaps growing up in the shadow of this majestic snow-capped peak gave Greg a natural desire to climb mountains. At the age of eleven he climbed to the top of Mount Kilimanjaro.
Greg was the oldest and only boy. He had three sisters. The youngest, Christa, was born when Greg was twelve. When she was eight, she began to have seizures. They found out she had epilepsy. Greg was always her protector.
His family didn't have enough money to send him to college, so Mortenson served in the U.S. Army in Germany from 1977-79. He was trained as a medic. He graduated from the University of South Dakota in 1983 with a degree in nursing and chemistry. He went to work in California as a nurse, and he continued his mountain climbing hobby. On July 24, 1992, he fell eight hundred feet while climbing and injured his shoulder. That same day, his sister Christa died of a seizure.