Oct. 9, 2009  -- Mark and Scott Blankenburg of Hamilton, Ohio, are identical twins. But the 53-year-old siblings share many traits beyond their identical facial features.

They're both pediatricians, and for years, the two men were well regarded professionals with successful practices. The brothers also lived together and neither one was married. They were both budding amateur photographers -- taking hundreds of pictures at Hamilton High School sporting events. Now the siblings share something else as well -- they're both facing multiple sex charges involving young boys.

"This is a very bizarre case ... I have been doing this for 25 years, and every time I think I have seen the most bizarre, weird case, another one comes along and this one is it," said Robin Piper, the prosecuting attorney for Butler County.

The case against the twins is basically this: Prosecutors allege that, for years, both men had sex with underage males -- including some patients.

In some cases, prosecutors allege, the doctors paid for that underage sex, other times they bribed the teens to keep quiet. In addition, Mark Blankenburg is charged with providing prescription drugs to minors.

Piper said that a search of the men's home and office revealed thousands of photos of teen boys, including "316 photographs of one kid basically bending over." Prosecutors charge that the photos and the graphic sexual fantasies demonstrate an unhealthy obsession with young boys -- one that spilled over into criminal behavior.

The men will be tried separately because the judge ruled that their identical appearances might confuse the jury. Mark Blankenburg is facing 41 charges. Scott Blankenburg is charged with 22 counts.

The Blankenburg trials have sparked a lot of interest in the criminal justice community. "It's very rare. I know of no other case where ... not just identical twins, but brothers, professionals have been charged with crimes of this nature," said Stephen Holmes, an associate professor of criminal justice at the University of Southern Florida.

Identical Twins Share Bad Behavior

Nevertheless, there is a lot of evidence to show that identical twins share plenty of basic behavioral patterns. According to Holmes, studies have found a strong genetic link in twins for negative behaviors, such as persistent lying, bullying and stealing. Further, Holmes said, "studies show that twins share more behavioral patterns than brothers and sisters, and that includes criminal behavior and aggression."

The correlation is even stronger for identical twins.

Studies conducted between 1929 and 1961 show that 60 percent of identical twins share criminal behavior patterns, compared with 30 percent of fraternal twins who matched on criminal behavior, according to Holmes.

The fact that the men lived together makes this case even more intriguing for researchers because it's difficult to tell whether their shared DNA or shared experiences might have prompted the men to commit the alleged sex offenses.

"Some people have urges and fantasies and never act on them because they know it's wrong and they think they're the only ones. But when you interact with others who may have similar fantasies, then you begin to rationalize your behavior," said Holmes, who co-authored a textbook on criminal sexual behavior "Sex Crimes: Patterns and Behavior."

Holmes noted that "twins are often exposed to the same stimuli" growing up and that "something in their adolescence could have triggered an interest in molesting children."

While their trials are separate -- Mark Blankenburg's case began this week and Scott Blankenburg will face a jury in April -- both men dispute the charges against them.

Trial Continues for Twins

"What I can say is my client adamantly asserts his innocence. You hear that all the time but this is genuinely his position that he has done absolutely nothing illegal," said Jack Garretson, Scott Blankenburg's attorney.

Garretson said the photos of high school boys may be numerous but they do not show any nudity. And, Garretson argues, any pornographic photos downloaded from the Internet show "persons who were over the age of 18." At trial, he also intends to prove that someone else downloaded those photos off the Internet -- not his client. As for the victims who claim to have had sex with the men? Garretson said his client maintains "they are lying."

Prosecutors admit some of the victims in this case have "difficult" reputations.

"Our job will be to get the jury to understand that, because these boys grew up to be young men with behavioral problems, that shouldn't discredit them from telling the truth about what happened to them when they were teens," said Piper.

And now at least one jury is getting a chance to decide what that truth is.