Siemon-Netto was born in Leipzig, Germany, where his devoutly Lutheran grandmother was the pivotal figure in his childhood in World War II. .

Siemon-Netto began his journalism career 1956 as a trainee at Westfalenpost, a large regional newspaper in southern Westphalia. In 1958, he joined the Associated Press in Frankfurt first as copy editor, then as slot editor and roving reporter, covering, among other things, the construction of the Berlin Wall in 1961. From 1962-1969, he worked as a correspondent for Springer Foreign News Service in London, Paris, New York, Vietnam, the Middle East and Hong Kong. His assignments included the United Nations, the U.S. civil rights movement, the assassination of President John F. Kennedy, the Vietnam War (over a period of five years),the Arab-Israeli Six Day War, and China's Cultural Revolution. From 1969-1973 Siemon-Netto was North American correspondent for the magazine, Der Stern, writing about many major news events in North, Central and South America, East Asia, France, and again Vietnam.

From 1973-1986, Siemon-Netto served as Managing Editor for Hamburger Morgenpost, taught journalism at Hamburg's Journalistenschule Henri Nannen, worked as a freelance correspondent for German, Swiss, French and U.S. publications, and as a media consultant overseeing a variety of design and management tasks at publications in Germany and the United States.

In mid-career, at age 50, he began his theological studies, first in Chicago, then in Boston. During these studies, Siemon-Netto freelanced as a magazine correspondent.At the time of the collapse of the Berlin Wall in 1989 and Germany's subsequent reunification, he served, concurrently with his academic work, as an editorial consultant and...as independent contractor...executive editor for Bild, launching its East German editions, helping plan newspapers for Leipzig and Dresden, training Eastern German journalists and developing a new curriculum for Journalistenschule Axel Springer.

From 1993-94 he managed the redesign of Der Tagesspiegel, a Berlin daily, the Scientific American, in New York, and idea-Spektrum, a Protestant magazine in Wetzlar, Germany. He also co-founded CA-Confessio Augustana, a Lutheran quarterly magazine in Neuendettelsau, Bavaria. From 2000-2005, he was religious affairs editor of United Press International and a Washington-based columnist for a variety of German-language publications.

He attended a variety of schools in Germany. He studied for his M.A. in theology