THE
how the myth of one gene was used to fuel racism … and
death by lethal injection.
Comic Books, Not Courtrooms
Comic book writers love the idea of a “warrior gene” or “serial killer gene” to create cheap drama. That’s exactly what this type of fantasy science is: entertainment. It belongs on a television screen, not in a real-world courtroom where human lives are on the line.
Real people are on death row right now because of fake science.
For years scientists warned this junk science would fuel racist stereotypes and lead to unjust sentences.¹
Courts allowed it anyway. That should terrify us all.
WHAT IS THE WARRIOR GENE?
In the early 1990s, researchers studied one single family in the Netherlands that had a history of violence and mental illness. Based on this tiny sample, they found a small variation in a lone gene called MAOA.² They claimed this tiny change in one single gene controls something huge: whether a person is born violent. Because of this, the media gave it a dramatic nickname: the "warrior gene."
The nickname stuck. The science didn’t.
What started as a small study on just one family turned into a massive, unproven theory used to judge people in courtrooms all over the world.
we cannot let junk science decide who lives and dies.
bad
science.
ridiculous arguments.
You may have first heard about the "warrior gene" on a TV show or in a comic book. Maybe you saw it on Riverdale, where a teenager discovers she carries the "serial killer gene" and spends seasons wondering if she's destined to become a murderer. It made for great television. It was also completely fake science.
Whether it was life imitating art or the other way around, in reality the entire "warrior gene" argument was also based on fake science, resting entirely on just one study: the Caspi Study. In 2002, a researcher named Caspi tracked a group of children in New Zealand.
The main conclusion: one specific gene, plus childhood abuse, produces a violent person.
Think about how ridiculous that is. Scientists have discovered that it takes at least 16 different genes working together just to determine a person’s eye color. Eye color is a simple physical trait. If it takes a massive team of 16 genes just to paint a shade of blue or brown onto a human iris, how could a single gene ever dictate something as massive and complex as human violence? It can’t.
It gets worse.
The main conclusion of the Caspi Study was based on only 13 people. Out of those 13, only 4 had violent criminal convictions. Four people. One gene. These findings were presented as “science” that could be used to predict dangerousness in anyone where this “warrior gene” was present.
Despite the shaky ground the original study was based on, multiple scientists tried to recreate Caspi's findings. They failed. The largest attempt, using 1,002 men, could not prove the same thing. The researchers themselves said the original finding "does not appear to hold true across different groups of people."
Furthermore, the later study was only done on males, and they were mostly white. Yet, it was used in American courtrooms against people of every race, including Black men. Riverdale's writers did better research than either study.
junk science in the courtroom
11
Criminal Cases
9
States
3
Death Sentences
Between 1995 and 2016, the “warrior gene” junk science branded 11 defendants⁵ as natural born killers. In 2016 one of those defendants, a black man in Texas, was labeled defective and dangerous – all but assuring the jury would sentence him to death.
That same year, the National Institute of Mental Health formally concluded that this type of research "should be abandoned." They said the study didn't look at enough people. They called the explanations it produced false.
Not questionable. Not outdated. False.
Ten years later that Black man in Texas is still on death row. The NAACP Legal Defense Fund called his case what it was: using false science to uphold the same racial stereotype the Supreme Court had already rejected: that Black men are inherently violent. They took their argument to the U.S. Supreme Court in January 2026.⁶
On March 30, 2026, the U.S. Supreme Court
refused to even hear the case.
The Supreme Court isn’t the only court turning a blind eye to this deadly injustice. Lower courts are still upholding life-and-death sentences based on a genetic myth that belongs on TV and in comic books.
We cannot let junk science decide who lives and who dies. You can do something about it. Join us today to help expose the truth and demand fair trials for everyone.
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Voices for Clemency