According to the Center for Sex Offender Management, a part of the U.S. Department of Justice, between 12 and 14 percent of sex offenders are known to have repeated their crimes. The data does show, however, that many sex crimes go unreported and the statistic could be low.
Karen Baker, the director of the National Sexual Violence Resource Center, said that she thinks the YMCA is right to screen their members' history for sex crimes.
"Certainly for any activity involving children at the Ys, it's probably a good idea to do that kind of screening," said Baker. "Wanting to keep children safe always trumps wanting to help an adult rehabilitate themselves."
But Baker agreed with much of what Shannon said, adding that there is a fine line between protecting children and isolating one-time criminals who want to make a fresh start.
"If we really want communities to be safe and we want people who have offended children to change their behavior and lead a more responsible productive life, we have to give them a chance," she said. "If we make it so hard for them to have any kind of normal life, then we are increasing their stress, driving them underground and making them much more dangerous."
Shannon said that of all places reformed criminals should feel welcome to go, it's their local YMCA.
"The whole idea here is that all of us have done stuff in our past that we're ashamed of," said Shannon. "We're all struggling to live as well as we can and people who have committed sex offenses, most of them are trying to seriously pull their lives together and integrate themselves into society.
"And certainly the YMCA should be there to help," he said.
The YMCA of the USA said in a statement to ABCNews.com that "each YMCA association is independent and autonomous, so local operational decisions are made by an association's volunteer board of directors and professional staff."
And Dwyer was not moved by criticism of the policy.
"We have a greater responsibility to the 35,000 children who walk through our doors and whose parents expect us to provide a safe environment. This is a perfect example of the needs of many outweigh the needs of the one," Dwyer said.