Born in a displaced persons camp in Eschwege, Allied-occupied Germany, Gejdenson was the child of a Belarusian father and Lithuanian mother.

During his tenure, Gejdenson had a number of very close campaigns for re-election, only crossing the 60 percent mark three times.

[1] Munster formally challenged the results, which were upheld by the Republican-controlled House Government Reform and Oversight Committee by a vote of 2-1.

In November 2000, Gejdenson unexpectedly lost his bid for re-election to the 107th Congress to state Representative Rob Simmons.

It was also alleged by author Jeffrey Benedict that Gejdenson had been an advocate of letting the Pequot Indians build the Foxwoods Casino.

Gejdenson is on the board of directors of the National Democratic Institute and was a Commissioner on the United States Commission on International Religious Freedom from 2012-2014.