SAN DIEGO -- A local psychologist told 10News John Gardner's childhood could explain his behavior as an adult.

10News spoke with psychologist David Gruder, who said, "Children learn from modeling. All of us learn from what's modeled to us. Not from what we're told."

10News learned Gardner's mother, Cathy Osborn, is a member of the Hash House Harriers, an adult running club. Pictures obtained by 10News showed club members, including Osborn, partying half-naked or completely naked after a run.

Gruder said any child exposed to such behavior would be impacted.

"If this is part of the environment that a child grows up in, then that child starts to believe as a child that this is part of what's normal and that it's OK for them to follow in those footsteps," said Gruder.

There is no proof that Gardner ever saw his mother with the club or knew about it.

Meanwhile, a childhood friend of Gardner's told a Lake Arrowhead (Riverside County) newspaper that as a teen Gardner admitted to having bipolar disorder. He also said he had been sexually abused by a male member of his family.

Gruder said that shouldn't be a surprise because many sexual predators were victims themselves, and those victims react differently as adults.

"They'll either go to one extreme where they become very, very asexual or anti-sexual, or extreme in terms of their hatred of sexuality or they will go to the other extreme or become very indulgent in their sexuality. But that indulgence can take many forms," said Gruder.

Gruder said none of what happened in John Gardner's childhood is his fault.

"The responsibility for doing the damage is of course on the shoulders of those who did not parent this boy properly," Gruder said.

However, according to Gruder, Gardner's actions as a 20-year-old, when he was convicted for committing a lewd act on a 13-year-old girl, cannot be blamed on anyone else.

"The responsibility of adult actions is squarely on our shoulders as adults and not with our parents anymore," Gruder explained. "That's part of what being a mature adult requires of us."

Gruder said the only time someone else could be held responsible is when the suspect is a ward of the state and considered insane, and Gardner was neither.