I am tall, lean, and physically powerful. At age 47, I still take medicine for acne. I have a temper that I work hard to control. And I've learned to avoid situations that set me off. I have never physically hurt anyone in anger.

I've got my faults. I'm a macho, generally well-liked man who enjoys being single and tries to live clean. There's been some romance, and no real problems here. A few women have even said I look okay and/or am a nice guy.

My muscles are stronger than they are coordinated, so I've focused on strength-endurance sports like gymming and swimming. But I'm a fair keyboard player.

I've got a pectus chest deformity and a wiring problem with my left eye. Cognitively, I'm a little "different" and always have been. But it doesn't bug me.

Uhh... do I sound like something you've read about recently?

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If you are visiting, you probably:

• have a child who has been genetically tested and found to have the XYY karyotype;


• have an unborn child found incidentally to have XYY, and want to know whether to continue the pregnancy and/or make special preparations for a problem child;


• are preparing a report on genes and behavior.

Most males have the 46-XY karyotype, but about 1 guy in 1000 has two Y chromosomes, and is an XYY ("diplo-Y", "diplo Y", "YY", "polysomy Y", "Jacob's syndrome"). If XYY men are at any greater "risk" of fathering XYY or XXY sons, the increase is small (Zygote 7: 131, 1999; <=1% Reproduction 121: 655, 2001).

When first discovered, popular science writers speculated that the extra "Y" would make owners act more masculine -- i.e., more aggressive, irresponsible, and criminal. Uh-huh. Richard Speck, the killer of eight student nurses, pretended (falsely) to be an XYY to obtain leniency, thus popularizing the "XYY's are criminals" story. The famous Nielsen letter in Lancet Sept 7, 1968 claiming that the prevalence of XYY men in prison was "25-60 times as high as the prevalence in the general population" remains a shocking example of how to mislead the public using small-sample statistics -- there were only two XYY's identified in the study. Aliens 3 was set in an offworld "penal colony for XYY's", and folklore continues to this day.

There's no question that XYY's average substantially taller, tend to be wiry-built, and tend to have severe acne. Minor birth defects -- like pectus, crooked eye, and minor outturning of the elbows, are supposed to be common in XYY's.

It will probably not surprise any adult visitor to this site that the average blood testosterone (the rocket-fuel that drives male sexual characteristics and behaviors) averages much higher in some men than in others. XYY's average higher than XY men. Men in prison average higher than men not in prison. When you control for the high testosterone levels, the most recent published study (Arch. Gen. Psych. 41: 93, 1984, from Copenhagen) showed there is no over-representation of XYY men in prison. ("Information from social records, a structured psychological interview, and projective tests did not support the notion that men with sex chrmosome anomalies are particularly violent or aggressive.")

XYY's average only slightly lower intelligence than XY's, and the range is the same for both groups. If XYY's really exhibit severe behavior problems, it has resisted demonstration by the best scientific minds in the field of genetics. Here's why -- it's something called "ascertainment bias". Kids who are screened for chromosomal problems tend to be learning and/or behavior problems. If they come up with XYY, it's easy to blame the karyotype. What's more, somebody doing bad science can get up a series: "Look at all the XYY's I've discovered, and most of them have mental problems!" (See the fallacy?) But to date, nobody's shown that XYY's are more common among kids who are screened for these problems than in the general population. And if XYY was itself a major problem, you'd think this would have been accomplished long ago.

Now, XXYY boys traditionally been considered at increased risk for emotional and cognitive problems. (For an update on XXYY from a parents' group, see http://xxyysyndrome.org/". The condition is rare enough that we're still in the "single case report" stage; the most recent work seems to confirm the prevailing wisdom, but once again, we don't see the picture of violent criminals (Arch. Gen. Psych. 56: 194, 1999), and one always wonders about ascertainment bais. The extra "Y" in an XYY is obviously not silent (as is the extra "X" in a XXX woman). It seems likely that the second "Y" adds a bit more aggressiveness to a man's overall personality. And I don't know that this is necessarily a bad thing. Despite decades of male-bashing from the Left, I think most people still like a man (or woman) who is responsibly aggressive.

When I'm certain I won't lose my own health insurance, I'll find out for certain whether I am an XYY. In the meantime:

• I have the phenotype, and...


• I like it, and...


• most folks who know me like it, too.

After reviewing the evidence, I find no reason to think that XYY makes men crazy, retarded, or criminals.

If you are considering ending the life of your unborn child "just because he is an XYY", don't do it.

Dr. Greene's XYY notes.

A site called Intersex Resources for Christians is now down.

I was pleased to be listed among these people's resources. There are at least two schools of thought in Christian circles about birth defects.

1. Some Christians believe that God micromanages the world. Specifically, many of these people will tell you that God causes birth defects, for His purposes. And they may even tell you that you are wicked if you don't like them or try to have them corrected.

2. Other Christians believe that God does not micromanage the world, and that birth defects are accidents of nature. If you have a birth defect, or anything else that interferes with your working, playing, and/or loving others, and it can be corrected by human wisdom and technology -- then by all means have it corrected. You should be asked to accept and tolerate only the things that you cannot change. In the meantime, we are required to follow Christ in reaching out to misfits of all kinds and offering help of whatever kind we are able. We seek to create a world where any decent person can find acceptance and opportunity.

Both schools of thought agree that good often comes from seeming misfortune. My position, of course, is #2.

Ed's notes on genetics with references.

Current articles from the refereed medical literature:

Prenatal Diagnosis 17: 363, 1997. Around 1 boy in 1000 is an XYY, and most completely escape detection. "It would appear that most undiagnosed [XYY's] do not look or behave in a manner which prompts testing for a chromosomal abnormality."

Ciba Foundation Symposium 194: 248, 1996. On criminal law and genetics. "The chapter begins by examining the scientifically-discredited XYY defense."

Genetic Counseling 6: 197, 1995. "Shows that the frequency of mental retardation is not increased in XYY males in general." Only 24% of the XYY men -- despite the selection bias -- were considered to have interpersonal / personality problems. I don't know what their criteria were, but that sounds about like the "normal" guys.

J. Am. Acad. Child. Ad. Psych. 37: 286, 1998. From Harmon, Bender, Linden & Robinson at U Colorado School of Medicine. Focus on XXX, but "this longitudinal study has clarified that previously reported outcomes of severe psychopathology and antisocial behavior in individuals with sex chromosome anomalies are rare, and variability in behavioral phenotype is much larger than originally appreciated."

Can. J. Psych. 43: 619, 1998. A reseracher at U. of Toronto reports that two of forty boys referred for pervasive developmental disorder (autism and its variants) were XYY's. This speculative paper seems to me to be most likely founded on a coincidence.

J. Int. Disab. Res. 42 Pt 1: 8-12, 1998. Ann Arbor researcher has one XYY in a series of 75 boys with pervasive developmenal disorder. Again, this seems like a probable coincidence.

Cancer Genetics 90: 179, 1996. Japanese researchers do a large study and find that the old claim that XYY's were more at risk for leukemia / lymphoma was based on a few coincidences rather than any causal relationship.

Psych. Med. 29: 953-62, July 1999. Of 34380 babies screened at birth, the 16 available XYY's were followed up. This Scottish study eliminates the ascertainment bias described above, and supports the idea that XYY has a mild effect on behavior. The authors found significantly more criminal convictions among the XYY group than among a group of matched XY's. They also diagnosed "antisocial personality" more frequently in the XYY's. There are some problems with this study which should be considered before anybody takes these findings at face value. These include

• One of the 16 XYY's was a habitual criminal, and half of the total of 36 convictions of XYY men were his. If he'd been dropped from the statistical studies as an outlier, the "effect of XYY" on criminal convictions would have been far less impressive -- in fact, barely significant.
• No XYY committed a crime using a weapon. One of the XY's did. No one in either group had an alcohol or drug conviction. The XYY group had a disproportionate number of "breach of peace" and minor theft convictions.
• In the US, Canada, Denmark (Dr. Nielsen's country), and Japan, there are similar groups of men who were karyotyped as babies and are now young adults. Nobody has yet reported statistically significant associations with criminality from any of these countries. Perhaps there wasn't a habitual criminal in any of the other XYY groups to throw the statistics off.
• In the US, "antisocial personality" implies a lifelong, heartless disregard for the rights of others. By contrast, this Scottish study diagnosed "antisocial personality disorder" by a checklist including such things as getting divorced and having trouble on the job, and found 6 of 45 XY's to be affected as well as 6 of 16 XYY's.
• Analyzing the statistics, the authors concluded that if you controlled for the slightly lower IQ's among the XYY's, there wasn't even an increase in criminal convictions. The average IQ in the group with convictions was 90; the average IQ in the group without convictions was 96. The average for people is 100.
• There's one more consideration. The parents were very likely told at the time of karyotyping that their sons had "criminal genes" or something. We cannot know to what extent there's a self-fulfilling prophecy here.

Whatever issues I may have with this study, I think most people would agree with the author's conclusion:

The investigation provides some reassurance that the enhancement of liability to criminal behavior in XYY individuals is relatively limited.

Arch. Dis. Child. 80: 192, 1999. This review is by Shirley G Ratcliffe, who is one of the authors on the above paper, and it obviously describes the same small sample plus three new ones. Because the author did not mention that one of the XYY's in the study was a career criminal, readers might misunderstand her talk about a greatly increased conviction rate for XYY's.

Ed's home page

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Afterwards: I have received dozens of E-mails about this page from parents of XYY boys. Most of them shared that their sons showed no particular behavior problems. Several mentioned their sons having short fuses and being hard to handle when they are angry, but that's been all. Others have expressly said there's been no particular temper problems. To date, not one of them regrets bringing their boy into the world.

Only one correspondent so far has described a sociopath (i.e., a lifelong pattern of heartless indifference to the rights of others, even those who treat him with kindness). Since sociopathy is all-too-common, and the vast majority of sociopaths have a normal karyotype. Despite the correspondent's feelings about the cause of her brother's behavior, it is hard for me to see anything but a coincidence.

E-mail addresses of some folks with XYY sons...

twinkler@ilexonc.com. The family of XYY boy Hayden Winkler -- "a 4 year old who was prenatally diagnosed and is at top form for his age."

carsonrobbie@sbcglobal.net

Carol and Bob, delighted with their XYY son. If there is anybody who needs our help or just to talk about XYY syndrome please tell them to e-mail us!

Followup (2006): He is in school and doing fine, tall and thin and healthy.

Adam Molloy

Jomama26@aol.com
louise@lloyd8290.fsbusiness.co.uk -- son is Harry
rayco@speedlink.com
kenjen2@bellsouth.net
LadyGreige@aol.com
jomama26@panola.com -- Tommy and Vicky Watson are happy with young Joe
krspykreme@aol.com -- very happy with young David
alinemanuel@hotmail.com -- Virpi Sirbu writes, "I have a wonderful XYY husband". He is interested in corresponding with other XYY men and their families.
domain_master52@hotmail.com -- Jay Carswell is an XYY mosaic. He describes the bony fusion in the elbows. "I am very happy with who I am."

glaceir14@aol.com -- Matthew is a young adult who recently learned of his karyotype. He tells me that people are surprised to learn this, since they say he's "one of the nicest guys they know."

studyquestions@aol.com -- Lorenzo writes:

We have a son, 11 years old. We were counseled about an abortion before the child was born~ Today he had a checkup. He is perfectly fine at this stage. At the counseling session we heard same stuff about criminal behavior and aggression. I thought, that this unborn child was going to be a rapist. In any case, if I were to design my own child, I could not ask for more than what my child is already. High 90's percentile in math. Above average in language. A little awkward. Can pronounce almost anything written in the English language. Not aggressive, but often bossy with his own peers, kind to younger children.

mooselake4@yahoo.com.in. "Put a flag re: XYY in the' subject' section."

meudt@gate.net

spakizer@neogen.com Stephanie Pakizer is married to "a great guy wity XYY".

banjoid7@yahoo.com Mark LeMond, in Oklahoma, says he is the parent of an XYY son "who is truly wonderful at six months old." He invites other parents of XYY's to mail him.

mlwgds@telus.net -- Leanne and Mike Stewart are very happy with Greg, who's now a teenager. "What a cool kid!" "We have had people contact us to discuss their XYY sons with us. It has been a pleasure to let them know our son Greg is doing very well. He is now in grade 12."

Our XYY Son

Rachel Cooper (pseud.) has written a book about an XYY son called "Hidden Tears and Happy Smiles", available from Lucky Duck Publishing.

tootliht@aol.com

Toledo is a designer for machines, including the apparatus that is used worldwide for inhalation therapy, and some improvements on automobiles and welding machinery. His manufacturing company has 55 employees. He's a community leader and encourages others to let their XYY children have a chance at life. "I have to say that many people would not have been helped, if I were not born."

tonyg@wattscda.com

My wife and I consider our son a gift from God. As far as I'm concerned, he is going to be brought up no differently than any other child. It is my responsibility to be an effective and positive influence in his life. I cannot be judge and jury for parents with a son diagnosed as XYY. But I will say this. If you can be a little patient with more physical and aggressive behavior, but keeping in mind to channel it right away, there is no difference in my opinion. Stern and loving approach right off the mark is all I'm going to recommend.