It's a situation most people hope they will never be in - wondering whether the child they loved and cared for is, in fact, really theirs.
"We had that bond through his first years and he called me 'daddy,'" said Valley resident Chris Ybarra.
Ybarra loved his son Kyler. But when Kyler turned 1 year old, Ybarra said he began to worry that maybe Kyler wasn't his after all.
"I have dark features," Ybarra said. "He had blond hair and blue eyes and he started looking nothing like me."
Ybarra didn't tell his girlfriend about his suspicions. They had already broken up. Instead, he took his son to get a DNA test. And his suspicions were confirmed.
"It was just really hard for me to wrap my head around that the kid I had been caring for isn't even mine," Ybarra said.
So Ybarra appealed to the courts to be released from child support payments. But he was told that he was still responsible for child support.
"It's not something I can dodge, so I guess she got me," he said.
CBS 5 Investigates discovered Ybarra is not alone and that paternity is not always based on DNA - as far as the courts are concerned.
Signing a birth certificate, or acknowledging paternity, is enough to establish a person as the parent and therefore financial responsibility.
"The court has to think of the children first and foremost in those situations," said Steve Wolfson, a family law attorney.
Wolfson admits it's difficult to undo a paternal relationship, even if a person proves through DNA to not be the parent.
"If a lot of time has gone by, if bonds between that father or mother have already been established with the children, the court may be less likely to disturb that order," Wolfson said.
For Ken Smith, it's been a six-year battle to break paternity, even though the mother admits she had no idea who the father is.
"It's been a roller coaster," Smith said.
Smith has taken two DNA tests. Both prove he's not the father of 6-year-old Jayden.
"I was shocked," Smith said. "How do you have concrete evidence that says this is not my child, two DNA tests and a confession and I'm still being held to pay for a child that's not mine?"
Sen. Rick Murphy, R-Peoria, said he had never heard of this dilemma until CBS 5 Investigates told him.
"It's something I plan to look into," Murphy said.
He questions whether the women who allegedly lied to these men should be held criminally responsible.
"There should be something in the law that recognizes that they should not be locked into paying child support to a mother that has essentially defrauded them," Murphy said. "I think it's not appropriate for a court or anybody else to force that to continue."
In the meantime, Ybarra struggles to make the monthly $800 child support payments on his modest military salary.
"It's rough when I'm out there working, especially being infantry out there on the line protecting my country and putting myself out there," Ybarra said. "Meanwhile, I have this back home."
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