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Jean Carnahan (search) has a favorite joke about her politics-prone family.

"I often say it's a genetic defect," the former Missouri senator said.

Maybe the Carnahan clan does share a campaigning chromosome — on some Missouri ballots this fall, the Carnahan name will appear not just once, but twice.

Robin Carnahan (search) is running for Missouri secretary of state. Her brother Russ is running for Congress in St. Louis. Their father is the late governor Mel Carnahan (search).

Mel Carnahan did not live to see his final political victory. He won the 2000 U.S. Senate race in Missouri weeks after he died in a plane crash. Jean Carnahan was appointed by the governor and served for two years in her husband's place.

"I felt like the people who backed him and supported him wanted something to survive that plane crash," Jean Carnahan said.

Robin may have the tougher of the two Carnahan races. She faces Missouri's Republican House Speaker Catherine Hanaway in the contest. Russ is the clear favorite over Republican businessman Bill Federer.

Click on the video box near the top of this story to watch a report by FOX News' Steve Brown.