Every wondered if it's possible your parents aren't telling you the whole story? Recent research has shown that up to one in every 25 fathers may not be the biological parents of their children. A team of experts from Liverpool John Moores University recently conducted a study of paternity that found between 1 and 30 percent of all DNA tests prove that a man is not the father of the children he thought were his. Awkward!

According to Professor Mark Bellis, the head of research for the John Moores team, “For any father, identifying that the child they are raising is actually sired by another man can have substantial health consequences. Such knowledge can also destroy families , affecting the health of the child and mother as well as that of any man who is subsequently identified as the biological parent."

In the United States, 142,000 paternity tests were administered in 1991. By the year 2001, the number of tests done to determine the father of a child had increased to 310,490. Improvements in technology have shed light on infidelities that most likely would have gone undetected in years past.

Phil Reilly is a lawyer and a clinical geneticist, and has seen firsthand how damaging DNA testing can be in certain situations. Reilly has stated, “We’re at a point in our society where the DNA molecule is ascendant, and it’s very much in the public’s consciousness that this is a powerful way to identify relationships. Yet at the same time, more people than ever are adopting children, showing that parents can very much love a child who is not their own. The difference here for many men is the combination of hurt and rage over the deceit, the fact that they’re twice beaten."

The following 15 photos feature clueless men whose children are most likely not related to them.

15 Fool Me Twenty-Six Times...Shame On Me

A man from Jericho, Utah recently uncovered the shocking news that he was not the father of any of his 26 children. Joseph McCallister, a fundamentalist who practices polygamy, and has 26 children from four different wives, recently filed for four simultaneous divorces after a paternity test proved that none of the children he thought he had sired were actually his.

McCallister became suspicious that something was amiss when a medical examination done by his doctor revealed that, due to a “testicular anomaly” it was not possible for him to father children. He hired a private investigator to get to the bottom of what was going on, and discovered, to his dismay, that DNA samples showed his twin brother, Brian McCallister, to be the actual biological father of all of his supposed children.

Brian, who is openly gay, admitted in court, “Mary, Joseph’s first wife, desperately wanted to have children but she hadn’t given birth two years after their marriage. She was desperate and asked me if I could help her out, and if at first, I refused vehemently, in time I eventually changed my mind. It wasn’t really like cheating since I’m a homosexual and had no desire for her. At first, it was supposed to be a one-time thing, but she came coming back every year.” Joseph’s other three wives soon began to wonder why they weren’t becoming pregnant. When they discovered what was going on, they demanded that Brian do the same for them. Brian continued, “They bullied me into doing this. They eventually got me hooked on crack-cocaine and crystal meth. I feel used, I feel like a dirty whore.”

14 Royal Ruse

Rumors have circulated for decades that James Hewitt, a former member of the royal guard, is the biological father of Princess Diana's second son, Prince Harry. The gossip never held much water because Hewitt always stood firm in his claims that he and the late Princess Di didn't begin their affair until little Harry was nearly two years old...that is, until a few years ago.

In 2014, Hewitt was suddenly singing a different tune. He told John Conway, a writer working on a play entitled Truth, Lies, Diana that he and Diana had actually started sleeping together approximately 18 months before little Harry arrived.

Add this information to the fact that Harry is basically the spitting image of Hewitt, and bears no resemblance whatsoever to his alleged father, Prince Charles, and it isn't too hard to believe that poor Charles is not the father of the ruddy playboy prince he raised as his own.

13 Something's Fishy

In some cases, one only needs to look at a child next to his father in order to determine that the two are not related, but in cases where the evidence is not apparent, advancements in DNA testing may have opened what researchers in the John Moores University study are calling a "Pandora's box of hidden sexual behavior."

They fear that the ease with which testing can be done, and the recommendations many experts are making for everyone to undergo some form of DNA testing, may not only be bad for families, but could be dangerous for public health overall.

The Liverpool John Moores University Team has acknowledged that one reason why men who undergo paternity tests are found not to be the biological father of their supposed children at such a high rate is because DNA testing is often a logical step to take when paternity is in question. In cases where testing is done for reasons other than paternity, men are found not to be the father only approximately 3.7 percent of the time.

12 Hillary's Infidelity?

It's common knowledge that former president of the United States, Bill Clinton, hasn't always been faithful to his wife, Hillary, but recent rumors circulating on the internet claim that the couple's daughter, Chelsea, is not Bill's biological daughter due to the former Secretary of States' infidelity. According to Radar Online, the notion that Bill is not Chelsea's father "is the best unkept secreet in Arkansas."

Allegedly, folks in Little Rock, Arkansas, where Bill was once governor, have been privy to this tidbit of juicy information for decades. Larry Nichols, a former Clinton aide, holds suspicions that Chelsea's actual father is Webster Hubbell, who is a former mayor of Little Rock. Nichols also claims that when Bill was once accused of getting a mistress in Little Rock pregnant, he combatted the allegations by admitting he was sterile. Nichols has stated, “We were discussing a woman’s claims that Bill had knocked her up and what we should do about it. But he denied that he could have gotten her pregnant. He said he had measles as a kid and that rendered him sterile. His exact words were, ‘I shoot blanks.’ Stunned by what I’d just heard, I asked him, ‘Then what about Chelsea?’ And he said, ‘Oh, Webb [Hubbell] sired her.'”

Hubbell's former brother-in-law, Finis Shelnutt, told The National Inquirer, “That was rumored in Arkansas for years and totally public. A lot of people suspected that. Chelsea kind of looked like Webb at that time. That is what a lot of people talked about. Of course Webb never discussed it with the family. It was just never brought up.”

11 Sorry, Honey

According to Mike, a father who was fooled by his wife into thinking he had fathered his daughter when, all along, another man was the biological dad, “It all could have been avoided from the beginning if she’d just told the truth. If she hadn’t led us to believe we were father and daughter, if she had just told me after she got pregnant that it might not be my kid.”

There is so much truth to Mike's statement. Child-welfare researchers, academics, government administrators and legal experts all agree that if paternity is established within the first few days of a child's life, it saves everyone involved from a lot of heartaches and headaches down the road.

Some feel DNA paternity tests should be a mandatory process at birth, and a 2001 Massachusetts Supreme Court ruling suggested that fathers should undergo a paternity test before signing any sort of a child support agreement because "to do otherwise places at risk the well-being of the children."

10 Kardashian Confusion

Rumors have circulated for years that Robert Kardashian, the late father of the first four Kardashian kids, is not Khloe's father. No one in the family has ever made an official statement on the subject, but tabloids have published story after story over the years speculating about who Khloe’s actual father may be.

Many have commented on the fact that Khloe doesn’t look like her siblings. She’s much taller than her two sisters Kourtney and Kim, and her facial structure is slightly different. It has also been reported that Kris was unfaithful to Robert during their marriage. Tabloids have made assumptions that Khloe’s biological father may be O.J. Simpson, Lionel Richie or Alex Rodan (Kris Jenner’s hairdresser at the time of Khloe's arrival.)

It was reported by InTouch magazine that momager Kris Jenner paid Rodan off, which is why he has never spoken out publicly about the possibility of being Khloe’s father. Lionel Richie has released an official statement claiming that Khloe is most definitely not his love child. As for Simpson, he has reportedly told friends in off-handed comments that he thinks he may be Khloe’s real father. What’s the truth? We may never know, but all signs point to the fact that Robert Kardashian is not Khloe’s father.

9 Who Is Daisy's Daddy?

Fashion model Daisy Lowe, whose mother is former indie singer Pearl Lowe, spent the first 14 years of her life thinking her father was her mother's husband, Bronner Handwerger. Daisy's world was turned upside down when a paternity test revealed that musician Gavin Rossdale was actually her biological father.

During her marriage to Handwerger, Pearl allegedly had a 5-year-long extramarital affair with the Bush front man. She has admitted publicly that when Daisy was conceived, Gavin forbade her to get a DNA test to find out whether or not he was the father. Instead, Gavin was made Daisy's godfather and had a good relationship with the family throughout Daisy's life.

After the truth was revealed, Daisy became closer to her biological father, his wife at the time, Gwen Stefani and his other children. Sadly, her relationship with Handwerger has been strained in recent years, despite his attempts to maintain it. He has shared, "For 14 years Daisy was my daughter. I doted on her like any father would. Things didn’t work out between me and Pearl, but I was determined to be a huge part of Daisy’s life."

8 Hate To Break It To You...

A 2009 article published in The New York Times entitled "Who Knew I Was Not The Father?" states, "There is a cultural imperative that a man should never abandon his offspring: that a man who impregnates a woman should be responsible for their child, and that a man who acted as a child’s father should continue to nurture her. But what is the cultural standard when those roles are filled by two different men?"

The article continues, "Judges, legislators and policy makers have floundered trying to reconcile the issues--a tangle of sex, money, science, betrayal, abandonment and the competing interests of the child, the biological parents, the non-biological father and the state itself."

A law professor in a 2007 Florida court wisely stated, "The laws should discourage adults from treating children they have parented as expendable when their adult relationships fall apart. It is the adults who can and should absorb the pain of betrayal rather than inflict additional betrayal on the involved children.”

7 Where Did Those Blue Eyes Come From?

Iconic filmmaker Woody Allen and his former lover, actress and model Mia Farrow, have three children together...or is it two? Farrow has 14 children between those she has adopted and those who are hers biologically, one of whom is Allen's current wife.

In a 2013 interview with Vanity Fair, Farrow dished that one of her sons, Ronan, may not be Woody's flesh and blood. She went on to hint that none other than the legendary singer Frank Sinatra may be Ronan's biological father. Lots of people have affairs, but this revelation is a bit more scandalous than most. Why? Mia claimed under oath that Ronan was undeniable Woody's, and, as a result, got a substantial amount of child support from the acclaimed director.

Following Mia's revelation that Ronan was "possibly" Sinatra's son, the child in question took to Twitter to speak for himself. He wrote, "Listen, we're all *possibly* Frank Sinatra's son." All speculation aside, when photos of Frank and Ronan are put side by side, it's difficult to dispute the fact that they share a certain debonair charm and both possess stunningly sparkling blue eyes.

6 There's More To This Story Than Meets The Eye

Tanner Pruitt of Texas became suspicious when, as his daughter grew older, she looked less and less like him. When she was 12, he sent some of his little girl's cells into a lab to find out the truth once and for all. The results confirmed his fears: he was not the father. He divorced his wife, but was required by law to continue paying child support.

Pruitt told The New York Times, "I spent thousands and thousands of dollars, and it hasn’t cost that biological father a penny, and yeah, I’m angry, but it would have been more harm to her psychologically than it was worth."

Despite the fact that she wasn't his biologically, Pruitt eventually got full custody of the daughter he had raised as his own since birth. When she was 15, the girl learned that the only father she'd ever known was not the one who sired her. After she found out from a relative, Pruitt told her the whole story. He shared, “When it was all over with, she gave me a big hug and told me I’d always be her daddy. Even though she’s not my blood daughter, I was there the day she was born, and I’ve been there ever since, so she’s my daughter, and as long as she’s alive, she’ll always call me Dad."

5 Even The Dog's Not Buying It

Another man, Mike, shared of the day he learned his little girl was not biologically his, but actually biologically belonged to another man named Rob, “The day the results came back was the most devastating day of my life. I ran upstairs, locked myself in the bathroom and cried and dry-heaved for 45 minutes. I felt like my guts were being ripped out.”

Despite the devastating realization that he had been fooled into thinking a precious child was his own, Mike is another man who has decided his daughter will not suffer as a result of his former wife, Stephanie's mistakes. He has shared, "Just because our relationship started because of someone else’s lie doesn’t mean the bond that developed isn’t real.”

Just like Pruitt, Mike was ordered to pay child support after his divorce from the girl's mother was finalized, and he didn't think it was fair. He fumed, "The courts insist on the best interest of the child...but it was in the child’s best interest for Stephanie and Rob not to do this in the first place. So why is that burden all of a sudden put on me?”

4 More Than A Feeling

When another man, Mr. Smith, learned that 11-year-old Chandria, the girl he believed was his daughter, was not biologically his, he chose to cut ties with the daughter he had raised since birth and her mother so he wouldn't have to bear the burden of child support. Smith has stated, “We’re penalized for trusting our wives or girlfriends!”

Chandria, who is now 20, has suffered greatly as a result the whole mess. She told The New York Times, “I was just a kid, so I didn’t really understand what happened or why. He never did explain why he didn’t want anything to do with me anymore.”

She continued, "It kind of wrecked my self-esteem. Even now, I worry about being a burden on people. I don’t want to be in the way. I don’t want to be anybody’s problem. It’s made me apprehensive about getting attached to people, because one day they’re there and the next day maybe they won’t be. You can’t help but be careful. He was what a father was supposed to be, but when things changed, he completely disconnected. That’s just not fair. You’ve been in my life my entire life and for you to just cut that off for money, well, that’s not fair to anybody.”

3 Liv's Discovery

It's common knowledge that Liv Tyler didn't know the truth about who her father was until her teenage years. She spent the formative years of her life believing that her dad was musician Todd Rundgren. Her mother, model and Aerosmith groupie, Bebe Buell, was with Todd when Liv came into the world. Todd was aware he wasn't the baby daddy from the beginning, but was there from the very start, even cutting the cord after Liv arrived. All the while, Liv's biological father, Steven Tyler was living it up on tour enjoying drugs, sex and rock n' roll.

Rundgren recently admitted, "I would love for Steven Tyler to have taken responsibility at the time. But for me, the adults were such children themselves that I thought, 'Well, how can a little girl grow up thinking that nobody wanted to be her father?'"

He continued, "It was not like I was a dummy, or completely unaware of Steven Tyler. As far as I'm concerned she's still my daughter and I'm still incredibly proud of her, and I love her, and whenever we get together it's just blissful--for both of us." What a great dad.

2 Not Fooling Anyone But Dad

Carol McCarthy is an officer of the Pennsylvania chapter of the American Academy of Matrimonial Lawyers. She has seen her share of heart wrenching paternity cases. McCarthy has stated, “Having been involved in cases like these, I think the answer to ‘Is it my kid?’ is irrationally important to the cuckolded husband. My own biases are going into this because I’m adopted, so I’m real into ‘your parents are the people who raise you.’ I couldn’t care less who my biological parents are. My parents are the ones who went through all the crap I gave them growing up.” She's got a good point there.

In the last decade, the number of paternity tests taken have increased by 64 percent. Usually, the men taking the tests are already unsure about the likelihood that they are the father of the child or children they've raised.

Surprisingly, even when men have DNA evidence to prove they are not the biological father of a child, this is often not enough to get them out of paying child support. The New York Times states, "The scientific advance that was supposed to offer clarity instead reveals just how murky society’s notions of fatherhood actually are."

1 Rob's Revelation

Rob Kardashian and Blac Chyna are notorious for the drama that is created when the two of them get together. While Blac Chyna was pregnant with baby Dream, rumors circulated that she slept with Glee alum Pilot Jones while she and Rob were on a break. What did this mean? It was possible Rob was not, in fact, the father of her bun in the oven.

On the season finale of Rob & Chyna, a paternity test revealed that Rob was the father of their baby-to-be. However, since the revelation, a source close to the couple revealed to Radar Online, "He's got it in his head that Chyna faked the first paternity test." So is Rob the father of baby Dream, or is he yet another poor man who has been duped by his lady love into thinking he fathered a child that was actually sired by someone else? We'll be waiting with bated breath for further developments.

Any man who has been through the agony of discovering a child he has cared for and loved is not his own has every right to be furious. The men who choose to continue being there for children even after discovering they are not their flesh and blood are truly heroic.

Sources: TheGuardian.com, TheAtlantic.com, ContactMusic.com, NYTimes.comWorldNewsDailyReport.com, TheTrentOnline.comLifeandStyleMag.com, InstantCheckMate.com, HollywoodLife.com, DailyMail.co.uk