Born in Langenfeld, Germany, Rathgeber was influenced at an early stage by Sesame Street and The Muppet Show which were broadcast on German TV. After school, he studied Communication Design at the Los Angeles Art Center's College of Design and worked in the advertising and game design industry. In 1992, the Jim Henson Company sought German puppeteers to work on the production of The Secret Life of Toys, which was to be produced in Duesseldorf. Rathgeber, Jurgen Tombers and Marcus Hübner were three out of 40 puppeteers who finally got the job.