Yang Heping enjoys his life in Beijing, having previously lived in the United States. [Photos provided to China Daily]

Before Yang Heping realized he was really Fred Engst, he struggled with his American identity, something he only discovered when he went home for the first time at the age of 22. Han Bingbin tracks that journey.

When Yang Heping was 3, he noticed that he looked different from those around him and that people stared at him on the streets. Before he returned to the United States in 1974, Yang, whose Chinese name was given to him by Madame Sun Yat-sen, could only imagine what his homeland was like. He felt like an adopted child wondering what his natural parents were like.

For Yang, 70, his relationship with his own country and relatives was something intangible and abstract, just like the fact that he was really Fred Engst, son of two Americans who had come to China in 1949 to be a part of history.

Yang's father Erwin Engst, a young farmer, came to join the communist revolution after he was inspired by the book Red Star Over China written by Edgar Snow. Two years later in Yan'an, where he was serving as a farm equipment expert, he married Joan Hinton, also from the US.

Hinton was a physics scientist who had been involved in the Manhattan Project, the atom bomb program. But she resigned after seeing the horrifying destruction the bomb caused in Hiroshima and Nagasaki in 1945.

After refusing more profitable job offers, the Engsts later spent the rest of their lives on the suburban farms of Xi'an and then Beijing, devoting their energy and expertise to fueling China's agricultural development.