Nature vs. Nurture: XXY and XYY chromosomes in men

Nature vs. nurture seems to come up pretty often. How influenced are we by our genetics and how big of a change can our surroundings make? Can our family, friends, media, education impact our personality more than our DNA? I am always more for inclusion than for exclusion so I urge you to take both things under consideration and instead of vs. use "and". Today we will see what characteristics, physical and psychological have men with an extra chromosome.

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The term X-men really gets a new meaning after this but another term Y-men also appears. Them being superheroes or not is up to you to decide but I will tell you this, they are not regular ordinary people. Their genetics is quite different from that which we call normal and the funny thing is, there is not like 5 of them in the world, it happens in 1 out of every 1000 men. Because of these numbers, it is still considered a rare condition but it is not as rare for you to not have a possibility of meeting a person with it or having him in your life. In the United States, there are approximately 10 XYY babies born every day.

Everything about how your body looks and works is written in your genes. Same goes for me and any other human being. Our hair, height, predisposition to various diseases etc. Every nucleus of a cell in the human body has the same complete set of genes. Chromosomes are little compact packages of DNA (deoxyribonucleic acid) and proteins that contain the genes for encoding the genetic features of every organism. A liver cell is different from the heart cell because some genes are active in one place and others in another place.

Genes and chromosomes

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Humans normally have 23 pairs of chromosomes, and every pair member is donated by each parent. The first 22 pairs are called "somatic" and the last pair forms the sex chromosomes. The sex chromosomes come in two kinds, X and Y. Females have two X chromosomes and males have XY. Most people get confused with the difference between chromosomes and genes so let me simplify. Imagine a chromosome is a book, genes are the chapters. DNA is a double-stranded molecule that is made up of four building blocks called nucleotide bases (A, T, C, and G) that are arranged in a certain order. Genes reside on chromosomes and we have 20,000-25,000 of them. They can be passed from parent to offspring and we call that inheritance. There are 3 different trait categories, depending on the patterns of inheritance; complex, dominant, and recessive.

COMPLEX TRAITS - the precise combination of genes contributing to the trait cannot be predicted, there is no obvious pattern and several generations are looked at for evidence of genetic influence for example heart disease or mental problems

DOMINANT TRAITS - they require only one copy of a gene to express the trait so if at least one of your parents could roll their tongue, that is enough for you to be able too and since you get genes from your mother and your father, your sibling may not get that gene and roll his tongue

RECESSIVE TRAITS - they require two copies of a gene to express the trait so both your father and the mother need to be a carrier of a gene for you to inherit it like with cystic fibrosis and of course, your parents may be only carriers themselves and you may become a carrier if you inherit one gene or have a trait if you inherit two of them

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Keep in mind that although our genetics pretty much remains constant during our life, they are not to be blamed for everything that happens because they RESPOND to the environment. Your diet, exercise levels, exposure to toxins, medications etc. influence your genes and traits. I have written "pretty much" because genes can change or mutate and some mutation is occurring all the time. It is harmful and has almost no effect on your traits because the body can most of the times recognize and destroy cells with harmful mutations. If you are interested in getting some more info about genetics, I recommend the fundamental topics related to human genetics from the US National Library of Medicine: Help Me Understand Genetics from Genetics Home Reference but it is safe to say that I have provided you with enough info so you can continue reading this post and follow along with no problems.

People with XYY syndrome (Jacob's syndrome) have an extra copy of the Y chromosome in each cell and are usually taller than average. This chromosomal change sometimes causes no unusual physical features and it sometimes causes changes in both physical and psychological development. Testosterone levels may be bigger so most of the movies and stories about men with XYY, portray them as extra aggressive and "super-male" which is not entirely true.

An increased risk for many things

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Learning disabilities and delayed development of speech and language skills are possible just as delayed development of motor skills and weak muscle tone. Hand tremors, asthma, and seizures are also symptoms of this syndrome but there is also the problem of an increased risk of behavioral, social, and emotional difficulties. ADHD, depression, anxiety, and autism spectrum disorder are all problems that may arise. Looking at all of this, it does not seem like you will get a manly alfa male filled with testosterone alone now does it? You would get a child that needs some extra love, attention and a different approach from his parents and educators.

Even though there is 1 in every 1000 children in the USA born with this syndrome, many of them are never diagnosed and most that are, receive the diagnoses later on in life. It is generally diagnosed when prenatal karyotyping is done for the detection of Down syndrome and other major conditions by amniocentesis. This chromosomal change usually occurs as a random event during the formation of sperm cells, it is an error in cell division (nondisjunction) and in most cases, the syndrome is not inherited. The reason why this error occurs is unknown. Keep in mind that this syndrome only affects men and it occurs randomly in pregnancies of women from all ages and ethnic backgrounds.

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The bad thing is that the syndrome has no cure for it because you can not correct every sex chromosome in the body but there is a plus size and it is hidden in the word syndrome. This is not a disease and people with it should not be considered sick. All we have to do is change our approach. Nurture and nature together produce amazing things. In most cases, people with XYY syndrome respond amazingly to intervention and treatment, and improve within a few years. Your genes can never be your excuse for a certain type of behavior. They may be "the blueprint" but is up to us to read that blueprint. Just because a person has an XYY syndrome does not mean he must become a criminal or have behavioral problems.

There was a cohort study to investigate the criminal pattern in men between 15 and 70 years of age diagnosed with XXY (will talk about that soon) and XYY syndrome. Crimes were classified into sexual abuse, homicide, burglary, violence, traffic, drug-related, arson and other. The incidence of convictions was increased in men with XXY and significantly increased among men with XYY but after adjusting the socioeconomic variables only some specific crime types like sexual abuse remained increased while others were similar to control group. This opens doors for a conclusion about an impact from socioeconomic conditions and kind of proves my point. You may be born with XYY but you will grow (be raised, impacted, influenced) into a criminal. The study is available here:

Criminality in men with Klinefelter's syndrome and XYY syndrome: a cohort study by Kirstine Stochholm, Anders Bojesen, Anne Skakkebæk Jensen, Svend Juul, Claus Højbjerg Gravholt

In conclusion, boys with XYY being more aggressive, more likely to have mental illness or more likely to become a criminal are all just myths and unfortunately, sometimes even excuses.

Just like people seem to think that men with XYY are manly and aggressive, they think that men with XXY are feminine and more gentle than those with normal XY genes. This is another misconception. In rare cases, a male is born with an extra X chromosome which is called the Klinefelter syndrome and most of them do not even know they have it until they experience problems with having children. Like the XYY, the XXY also has no cure but can also be treated and people live normal lives. There has been observed how older women have a higher chance of having a boy with Klinefelter but that rise in probability is so tiny that it is not even considered valid by most doctors.

Similar symptoms like men with XYY

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Men with this symptom, just like those with XYY, may have troubles talking, writing, speaking, and math but as XYY are extroverts and experience ADHD troubles, men with XXY tend to be shy, slow, and with low confidence. Low testosterone levels cause less body hair, smaller muscle tone and reproductive organs, low sex drive and infertility. That lower level of testosterone is the reason behind a greater chance for various autoimmune diseases, diabetes, heart problems, osteoporosis, and mental health issues. Testosterone replacement therapy helps in preventing some of the long-term problems that come with Klinefelter syndrome but counseling and physical therapy are also advised. As you can see, men with XXY have much bigger problems than those with XYY and still, I have a feeling like we are far more concerned with the potential aggression that has a small chance of happening in XYY than we are with real problems with high probability that men with XXY have.

What is interesting is that most boys after showing shiness, later on exhibit signs of an explosive temper, hyperactivity, and impulsivity but like with anything else, it depends on the environment they are in. If they get help with their common dyslexia problems and troubles with learning (present in 50% of the cases) they grow up to be normal, healthy, and socially adjusted with no signs of anti-social behavior so in a way, nurture wins again. To me personally, it is quite normal for a person to develop feelings and acts of anger and explosive temper if it is raised in an environment that is always trying to push him down instead of raising him up. With undermining a child and laughing at his shortcomings, there is absolutely nothing positive that can happen.

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Klinefelter syndrome affects males only; females cannot have it. It affects from 1 in 500 to 1 in 1000 men. Although I have written and most sources do tell you that there are no females with XXY, that is not entirely true. A few of them have been born and I did find a paper about a 17-year-old girl with XXY syndrome. She has a normal hormonal level and other biochemical parameters for a female which was not the case with previous women who had it. The conclusion of the study is that each individual case is unique and needs to have specific attention. The study is available here:

Case Report Open Access, A New Female Case with 47,XXY Karyotype and SRY by Hasan Acar, Hakan Taskapu, M. Hamza Muslumanoglu and Metin Çapar

This is not the first and will most certainly not be the last post that I will write about nature vs. nurture because I want the inclusion of those two to be accepted. Yes, your genes play a huge role in how your life is going to look like but they do not get to have the final say. XXY means lower levels of testosterone and XYY means higher levels of testosterone but both conditions can be treated and men can lead normal lives. There are people who eat whatever they want and in whatever amount and stay skinny. After much practice and self-work, I have learned not to hate them lol. There are also people who eat an apple and everything from that apple gets turned to fat (pardon the exaggeration). This does not mean that ALL people with genes for fatness are fat, there is this thing called exercise, I don't know if you've heard about it yet but it has been showing great results...