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©2024 American Medical Writers Association. All rights reserved.  
ISSN 2163-5315

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ABSTRACT
In recent decades, huge strides have been made in the field 
of genetics. Genomic analysis technology has enabled sci-
entists to explore how genetics affect every aspect of human 
life and development. Genetic testing is poised to be at the 
forefront of contemporary medicine. Parents often grapple 
with the correlation of their child’s genetic mutations and 
serious diseases. At a time when misinformation spreads 
through the popular press like wildfire, we are recounting 
the XYY story as a cautionary tale to highlight the impor-
tance of scientists speaking up and standing against the 
misuse of genetic information.

The visualization of human chromosomes in the 1950s 
opened an important era of discovery in biomedical sciences. 
Scientists Marthe Gautier and Jérôme Lejeune were the first 
to identify the extra chromosome that caused trisomy 21, 
better known as Down Syndrome.1 Karyotype analysis, or the 
analysis of human chromosomes, then led to the discovery of 
hundreds of other chromosomal variations that have proven 
to be essential for the diagnosis of genetic diseases. Although 
advances in genetics have led to effective treatments, they 
have also been used to draw lasting damaging and false 
connections between genetic profiles and human behav-
ior. Karyotype analysis eventually led the research group of 
geneticist Patricia Jacobs2 to ask whether an extra  
Y chromosome correlated with more aggressive behavior and 
criminality.
 The research for the answer to this question had many 
unforeseen consequences. The stigma that developed 
around XYY syndrome caused a cascade of unfortunate 
issues. In this article, we recount cases of inequality, pre-
mature pregnancy termination, and misinformation in the 
health care system regarding the XYY chromosome diag-
nosis. We showcase this example to make readers aware of 
how current cases of chromosomal variation could create 
bias in medical diagnoses.

REVIEW
XYY syndrome (also known as 47, XYY, and Jacobs syn-
drome) is a genetic condition in which individuals born 
with male sex, who typically have one X and one Y chro-
mosome, have an extra Y chromosome. The syndrome, 
which occurs in 1 out of every 1,000 individuals born with 
male sex, is shown by recent data to have effects on fertility 
and an increased possibility for an atypical neurocognitive 
phenotype. Although research is limited, there is evidence 
of slightly altered or slowed development of reproductive 
organs in people with XYY syndrome. Studies have also 
shown that supernumerary sex chromosome syndromes, 
including XYY, place children at an increased risk to show 
symptoms of Autism Spectrum Disorder.3

 The Jacobs team examined the karyotypes of inmates 
at the former State Hospital for the Criminally Insane in 
Carstairs, Scotland. In 1965, Jacobs et al2 published an 
article in Nature observing that 3.5% of inmates of the 
Edinburgh institution carried an extra Y chromosome. 
Although Jacobs et al2 concluded that the individuals with 
the XYY karyotype were likely not very different from the 
non-XYY prisoners, the article was poorly titled “Aggressive 
Behavior, Mental Sub-normality and the XYY Males.” The 
title apparently reflected what they were asking, not what 
they found, but it nevertheless suggested an association 
between the XYY genotype and criminality. The title opened 
the flood gates for popular news outlets to disseminate the 
information implied by the title as established scientific 
evidence. Science Digest and Time magazine reported on 
Jacobs et al’s2 research using headlines like “Chromosomes 
and Crime.”4 Although this was not the case, such stories 
in the press led to public concern about people carrying an 
extra Y chromosome. Bias against people with XYY was also 
perpetuated through various news stories. In 1966, 8 nurses 
in Chicago were murdered by Richard Speck. Because of 
miscommunication between a journalist and scientist, news 
spread attributing Speck’s homicidal behavior to his having 
the XYY mutation, even when blood tests proved otherwise.5

Helena I. Ebeling1 and Jonathan R. Beckwith, PhD2 / 1Undergraduate, Department of Biology, Boston College,  
Chestnut Hill, MA; 2Emeritus Professor, Department of Microbiology, Harvard Medical School, Boston, MA

The XYY Story as a Cautionary Tale: How Scientific Misinformation  
and Common Biases Can Negatively Impact Lives and Opinions

EVERYDAY ETHICS

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AMWAJournal.org     41The XYY Story as a Cautionary Tale

 In the years following the original publication, Jacobs’ 
claims of the link between XYY and criminality were fur-
ther disproved. It was revealed that many individuals in 
the study done by Jacobs et al2 who had the XYY genotype 
had committed petty crimes against property, not people.6 
Additionally, subsequent studies analyzing the proportion 
of individuals with XYY in criminal institutions never came 
close to the 3.5% that Jacobs et al found in their original 
study. Despite these findings, XYY testing and the stigmatiza-
tion of individuals with an extra Y chromosome continued.
 During President Nixon’s time in office, his personal 
psychiatrist, adviser, and confidante, Dr Hutschneker, sug-
gested that all 7- to 8-year-olds in underserved or poorer 
areas be karyotyped for homicidal or violent tendencies. If 
these children were an XYY match, Hutschneker suggested 
that they be placed in interventional institutions.5 This 
practice perpetuated an extremely dangerous stereotype of 
criminalizing people from marginalized groups, rather than 
attributing their behavior to their childhood, surroundings, 
or the racist biases that incriminate them.
 In 1973, a group of young researchers and doctors at 
Harvard Medical School in Boston, including Dr Jonathan 
Beckwith, learned that a researcher at Boston Lying-In 
Hospital was seeking pregnant women who might allow the 
study of their newborns to determine which, if any, male-
sexed newborns had XYY syndrome. The consent form 
did not disclose that the chromosome analysis was being 
supported by the Crime and Delinquency division of the 
National Institute of Mental Health.7 If the newborns had 
the XYY karyotype, Dr Stanley Walzer, who was leading the 
study, would contact the parents to inform them and offer 
his help and observation as the children grew up. The skep-
tical group of Harvard scientists, including author Beckwith, 
had seen the dangers in the XYY screening as a self-fulfill-
ing prophecy and proposed that Harvard Medical School’s 
standing committee on medical research evaluate the XYY 
screening protocol and potentially suspend it, if warranted.7 
After the Harvard committee initially stated that the study 
should continue, the critics of the project approached the 
Children's Defense Fund in Boston, which in turn contacted 
the Massachusetts Attorney General and the study was 
finally halted. The publicity from this halted study resulted 
in the cessation of similar studies elsewhere as addressed 
by Hamerton in his presidential address to the American 
Society for Human Genetics.8

 The New York Times covered the change in sentiment 
about the XYY karyotype in an article titled “A Chromosome 
Link to Crime is Doubted”9 in 1976. The article mentioned 
that the original conclusion that individuals with XYY were 
more likely to be criminals was false. Rather, it was more 
likely that the slight increase in criminality was  

typically caused by a lower intelligence quotient and Autism 
Spectrum Disorder associated with the chromosomal muta-
tion.9 The paper also interviewed Dr Witkin, an American 
psychologist who pioneered developments in perception as 
it related to learning. Dr Witkin suggested that society would 
not gain anything from identifying individuals with XYY and 
placing them into intervention. Rather, he recommended 
that the educational and cognitive deficiencies that were 
associated with the XYY karyotype should be dealt with 
when problems arise.10

 In 1982, 17 years after the publication of her original 
paper,2 Dr Jacobs retracted her initial statements saying, 
“In retrospect, I should not have used the words ‘aggres-
sive behavior’ in the title of my paper and should not have 
described the institution as a place for ‘the treatment of 
individuals with dangerous, violent or criminal propensi-
ties.’”11 Still, the XYY narrative persisted for many years in 
the media, with various episodes of Law and Order and the 
film Alien 3 featuring an antagonist with the XYY karyo-
type. A Hastings Center conference report in 1980 que-
ried various geneticists and scientists on their opinion and 
experience with the XYY controversy. Saleem Shah, an 
Indian-American psychologist who worked closely with 
mental health and the law, noted that when having the XYY 
karyotype made somebody a criminal, he “started to receive 
calls from attorneys asking what [he] knew about the extra Y 
chromosome and its relevance to the legal issue of criminal 
responsibility.”12

 Despite all the trouble stemming from the initial Jacobs 
et al2 XYY study, additional researchers over the past 30 
years have sought to link negative behavior to genetics. In 
1993, a Dutch group reported that individuals carrying a 
mutation eliminating the function of a gene for monoamine 
oxidase A (MAOA) were more likely to exhibit abnormal and 
sometimes violent behavior.13 Many of the individuals with 
this mutation came from the Pacific Islands, and the muta-
tion was named the warrior gene.14 As in the case of individ-
uals with XYY, the warrior gene was stigmatized, and those 
with the mutation were classified as aggressive or having 
violent behavioral tendencies.
 In a 2016 publication, a group of researchers in India 
claimed that the presence of Barr bodies, chromatin struc-
tures formed from the condensation of X-chromosomes, 
was linked to criminality in men. The article entitled “Do 
the Presence of Barr Bodies in male jail inmates indicate 
criminality: a pilot study”15 studied an exceedingly small 
sample of 100 inmates and concluded that individuals with 
Barr bodies were likely to become criminals.
 Articles with suggestive titles describing studies with 
faulty experimental procedures pose a great threat to sci-
ence and society. As in the XYY case, these studies are 

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AMWAJournal.org     42The XYY Story as a Cautionary Tale

overrepresented in the media. Deceptive media coverage 
leads society to promote false beliefs about various groups 
and instills fear of people with certain genetic makeups. 
Minority groups and low-income families or targeted racial 
and ethnic groups are the first to be marginalized and pre-
sumed to have conditions involving behaviors stereotypi-
cally associated with these groups.

CURRENT IMPLICATIONS
In more recent studies, scientists continue to use genetic 
ancestry to shape societal values. Increasingly, geneticists 
are working with social and behavioral scientists to connect 
certain phenotypes in a genetic ancestry to specific behav-
ioral and cognitive outcomes. Recent social and behavioral 
genetic (SBG) studies have determined that the phenotypes 
that some scientists say are predictors of one’s social, intel-
lectual, or economic outcome in life are no more predictive 
than family income and geographical location. Jonathan 
Beckwith once importantly noted that many flawed genetic 
studies attempt to “explain away problems by genes and dis-
tract attention from social conditions that cause problems.”16

 In an article published in “The Ethical Implications of 
Social and Behavioral Genomics,”17 the authors caution that 
if SBG studies analyzing phenotypes are to be conducted, 
they must be carefully reviewed, evaluated, and sometimes 
restricted from publication.17

 Genetic testing has its benefits as well. Genetic test-
ing helps physicians define chromosomal mutations and 
genetic disorders that may inhibit or alter childhood devel-
opment, so parents may be prepared and take preemptive 
steps for their child. It is when this genetic testing is used for 
purposes other than ensuring the health of an individual or 
the population, that it becomes a detriment to society.
 A world in which a person’s every trait can be predicted 
by their genetic ancestry and makeup is a very dystopian 
one. Although futuristic science and technology can act as 
forces of progress, they can just as easily spread information 
that can be used to alter societal opinions. It is our duty as 
scientists to speak up against bad science just as Jonathan 
Beckwith and his colleagues did during the initial XYY study.
 In the wake of the COVID-19 pandemic, the problem 
of misinformation is metastasizing—with more and more 
retractions from high impact factor journals, the demise of 
numerous online journals populated with manuscripts gen-
erated by paper mills, and the popularization of artificial 
intelligence (AI)-generated content. Scientists, editors,  
publishers, and even readers bear an increased respon-
sibility for preventing inaccurate or misleading titles and 
content from being published and popularized. Preventive 
measures could include a more thorough vetting of  

submissions for publication and soliciting of diverse opinions 
and expanded use of AI detection software that would  
prevent the use of computer-generated or modified images 
and content. Misinformation can spread like wildfire. 
Therefore, it is essential that scientists consider the broader 
social context and consequences of misleading, or frankly 
false, information.

Acknowledgments
Dr Beckwith has had a long and extremely successful career 
in the field of genetics and microbiology. In his early career, 
he led the research group that isolated the first gene from a 
bacterial chromosome, and his research continued to flour-
ish from there. Mostly notably, outside of his career in scien-
tific research, he is a controversial activist of social justice and 
civil liberties in the science community. He was an important 
organizer in the activist organization Science for the People, 
which fought against inequality and unethical practice in 
the field of science. He continued his career as the American 
Cancer Society Research professor of Microbiology and 
Molecular Genetics at Harvard Medical school.
 I (Helena Ebeling) am an undergraduate student at 
Boston College, with an aspiration for medical school.  
My interests mainly lie within genetics and scientific com-
munication as technology advances. Working alongside 
Dr Beckwith and his deep conviction in the importance of 
communication in the impact of science and society has 
sparked the same passion in myself.
 Dr Beckwith has more recently been struggling with an 
Alzheimer disease diagnosis. In an effort to keep the words 
of one of the most brilliant minds alive, he and I drafted this 
manuscript together as he recounted his efforts in the 1970s 
to prevent unethical research and shared his opinions on 
more recent ethical dilemmas. Together, we reviewed arti-
cles, studies, and news publications surrounding the con-
troversial case of the XYY karyotype, as well as paralleling 
current research. Dr Beckwith has been my inspiration as 
he continues to amaze with his knowledge and dedication 
to this cause. With this article, I hope that his insight can be 
passed on and be an inspiration for the future of medicine 
and research.
 I thank Emrah Altindis, PhD, for introducing me to 
Jon Beckwith, as well as Susan Michaelis, PhD, and Fariba 
Houman, PhD, for their suggestions and support in writing 
this article.

Author declaration and disclosures: The authors note no  
commercial associations that may pose a conflict of interest in 
relation to this article.

Author contact: hebeling2@gmail.com

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AMWAJournal.org     43The XYY Story as a Cautionary Tale

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https://www.nytimes.com/2001/01/03/us/arnold-hutschnecker-102-therapist-to-nixon.html
https://www.nytimes.com/2001/01/03/us/arnold-hutschnecker-102-therapist-to-nixon.html
https://www.nytimes.com/1976/09/12/archives/a-chromosome-link-to-crime-is-doubted-study-in-denmark-finds-no.html
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