From left, Department of Commerce General Counsel Cameron Kerry, his brother Sen. John Kerry and John Kerry's wife Teresa Heinz Kerry arrive at the Hart Senate Office Building on Capitol Hill, Jan. 24, 2013 in Washington. Chip Somodevilla/Getty Images.

Secretary of State John Kerry's brother took the unusual step today of writing an op-ed defending him against accusations by some Israeli politicians of being anti-Semitic.

Cameron Kerry, who converted to Judaism, wrote in the Israeli newspaper Yediot Ahronoth that "such charges would be ridiculous if they weren't so vile."

John Kerry's focus on Middle East peace talks was condemned publicly by at least one member of Israel's Knesset as containing "anti-Semitic undertones," and he has also been criticized by others, including the Israeli defense minister, for taking a "messianic" and "naïve" approach to talks.

In his brother's op-ed, which appears in today's edition of the Hebrew-language newspaper and is translated into English on the U.S. Embassy in Tel Aviv's Facebook page, Cameron Kerry details their ancestors' own experience with anti-Semitism. He noted that their grandfather, Frederick Kerry, was born Fritz Kohn in Czechoslovakia and, upon emigrating to America and joining the military changed his name and converted to Catholicism because of anti-Semitism in the ranks.

"All this is part of my brother John Kerry's DNA," Cameron wrote.

"I recall when he came home from his first visit to Israel with friends from the Boston Jewish community, more than thirty years ago as a young senator: he spoke vividly of flying an Israeli military jet over the country and realizing how it was possible to cross the country in a matter of moments. Today, his determined work on Middle East peace is informed by an abiding sense of the need to secure Israel as a home for the Jewish people," the op-ed said.

"It is this deep involvement that has led to the conviction that Israel's long-term security requires a two-state solution - that, in the face of the inexorable forces of security, demographics, and geography, Israel cannot sustain occupation of the West Bank and remain both democratic and Jewish."