"Right now, I think all anyone can hope for is to be able to talk to them," Bauer's sister Shannon, of Boulder, Colo., said in an interview as the families unveiled a Web site with information about the case.
The three have been in custody since they entered Iran from Iraq without authorization on July 31. Their case has become the latest source of friction between the U.S. and Iran, with Secretary of State Hillary Rodham Clinton appealing for their release.
U.S. officials and authorities in Iraq's self-ruled Kurdish region say the backpackers crossed the poorly marked border by mistake while visiting a scenic part of Iraq.
Iran's state television has said they were arrested after disregarding border guards' warnings, and a prominent Iranian lawmaker has said authorities were investigating whether to charge them with espionage - an allegation the U.S. State Department and the families have dismissed.
"We know who our siblings are, so we're not particularly concerned about that," Fattal's brother, Alex, said in an interview Thursday. They are, he said, curious about the world and "totally harmless."
He, Shannon Bauer and Shourd's brother, Chris Rapp, said the three planned the trip carefully and told relatives beforehand that they were heading for a scenic part of Iraq - not Iran.
"There was no hint or inkling that there was the slightest intention of going to Iran," said Alex Fattal, whose family is from Elkins Park, Pa.
The families said the three experienced travelers were visiting an area, famous for a waterfall, that often draws tourists.
Friends had told them "that this was a beautiful area and a safe area," said Rapp, of Boise, Idaho.
Shane Bauer, 27, is a freelance journalist. The Pacific News Service had hired him to cover the Kurdish elections. He and Shourd, 31, are dating and had been living in Damascus, Syria. She teaches English and has written for various online publications.
Joshua Fattal, 27, went to visit them after traveling overseas on a teaching fellowship with the International Honors Program from January to June.
All three are graduates of the University of California, Berkeley.
The United States and Iran have not had formal diplomatic relations since the since 1979, when militant students took Americans hostage for 444 days at the U.S. Embassy in Tehran.
Clinton issued a statement Saturday urging Iran to let the hikers go. Diplomats from Iraq and Switzerland, which represents U.S. interests in Iran, also have tried to intervene on the backpackers' behalf.