How Stress Creates Left-Handed People

Train in vain
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Are you left-handed or know someone who is?

Are there left-handed people in your family?

Left-handed people have been treated with suspicion for centuries.

Left handedness has always been with us. Historically it has been perceived as an anomaly or defect which meant that left-handed children were “trained” out of left-handedness.

Research On Left-Handedness

Because of concern about left-handedness, there has been much research done about left-handedness over the years. The research on left-handedness has been helpful because it is showing that left-handedness is not an isolated trait. It has, in fact, been correlated with many other conditions and diseases.

By investigating the relationship between left handedness and other conditions, the research community has unwittingly provided us with clues to the emerging identity of the highly sensitivity. The HSP trait  was named by Elaine Aron, Ph.D. in her book, The Highly Sensitive Person, in the 1990’s.

One of the most important research studies was conducted by Dr. Norman Geschwind. His work, often called the Geschwind Theory, shows that there is a relationship between maternal testosterone, lefthandedness, and genetic diseases.

What that means is that when a pregnant woman has very high stress levels, the testosterone in her body rises which causes the fetus to develop differently.  This condition can create left-handedness, the highly sensitive trait, and many genetic diseases, which can coexist. The New York Times profiled the Geschwind study in their article: Left vs. Right: Brain function Tied to Hormone in the Womb.

Another excellent resource for highly sensitive people on the relationship between left handedness and genetic diseases is the H.I.S.S. of the A.S.P, written by David Ritchey. This book discusses the relationship between prenatal testosterone due to stress, and the development of the highly sensitive person. David Ritchey cites the Geschwind Theory along with other research including his own showing the prevalence of left-handedness and genetic disorders among highly sensitive people or anomalous sensitive people  – his name for highly sensitive people.

Stress, Left-handedness And High Sensitivity

The human race has been suffering with high stress levels for centuries. When that stress affected pregnant women, humans were born with a wide variety of conditions including high sensitivity and left-handedness.  Over time, these and other genetic conditions have been passed down from one generation to another.

The research on left-handedness is providing us with the causal link between stress, maternal testosterone levels and the many human illnesses and conditions they create.  It would be helpful if it could make us more aware of how important managing stress is and the impact of ignoring it.


Stress in the Womb

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There is a growing awareness that stress in the womb plays a major role in the creation of genetic diseases and the highly sensitive trait.  Maternal stress during pregnancy results in higher levels of testosterone in the body and by extension a fetus. The higher levels of testosterone change brain development increasing the chance of genetic diseases, the highly sensitive trait as well as high creativity and giftedness.

The BBC  Mum’s stress is passed to baby in the womb reported recently about a study in the journal Translational Psychiatry showing that women under the stress of potential violence have children with a genetic change in the glucocorticoid receptor (GR), which regulates the response to stress, making the children more sensitive to stress.

The article discusses how a change occurs in methyation, an important biological process in “gene expression.”  The best lay explanation comes from Discovery. This is their description:

“Methylation is a process by which a gene’s behavior is altered, but the gene itself isn’t changed. This is almost like following all the directions in baking a batch of cookies correctly, except for the oven temperature. Even though all of the ingredients are the same, those cookies won’t bake — or behave — the same way when baked a couple hundred degrees lower than they should be.In methylation,  environmental exposures or different lifestyle choices have the potential to cause methyl groups, which are groups of one carbon and three hydrogens, to land on top of our genes and change how they are expressed. This, in turn, changes the ability of our genes to share the directions they contain for making our bodies’ proteins.”

Apparently, stress in the womb affects the methylation process during pregnancy, altering gene expression.  Methylation seems to be a major factor in the biochemical processes responsible for a fetus becoming a highly sensitive person.

This is just one study, but it points to an increasing awareness of the impact of stress in the womb in the creation of highly sensitive people.  It is an important tool for developing approaches to minimize genetic diseases of all kinds and shows us how genetic mutations and environmental factors can create unintended results.

For more information about the traits of highly sensitive people, HSP Health offers information about the biology and characteristics of HSP’s.

What Causes the HSP Trait?


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What causes the HSP trait? In the 1980’s the findings of an important medical study were released.  The study laid a biological and scientific basis for understanding the highly sensitive trait.

Dr. Norman Geschwind, a neurologist at Harvard Medical School, conducted a study of 3000 people with Dr. Peter Behan, a neurologist at the University of Glasgow.  He was attempting to discover the correlation between left handedness, learning disorders and genetic diseases.  The report, titled  “Cerebral Dominance” revealed his findings.

Apparently what causes the HSP trait is stress during pregnancy which sets a chain of events in motion that results in changes to the development of the child.  Higher levels of testosterone in the mother caused by stress cause the fetus to develop differently because the testosterone creates reserve lateralization of the brain. Reverse lateralization of the brain slows the left brain’s development as a result of the increased testosterone and advances a greater developed right brain.

One result is that brain functions may be located in atypical places in the brain -an example would be language skills changed to a location in the right brain;  speech problems may be a result.  Another result is a greater chance of  left-handedness, a known characteristic of highly sensitive people.  Since each side of the brain controls the opposite handed, handedness located in the right brain results in left-handedness – an HSP effect that is more pronounced in males than females.

The study that Dr. Geschwind did with Dr. Behan showed left-handed people were 2 and 1/2 more times more likely to have autoimmune disorders and 10 times more likely to have learning disabilities.  Near relatives of left-handed people can also be affected and may acquire HSP traits.  Apparently there is a familial genetic basis for these conditions so that any family member can be right handed and also experience learning difficulties, autoimmune disorders and other human genetic diseases because the family has a history of left-handedness and the highly sensitive trait.  It is possible that what causes the HSP trait in some individuals is a familial genetic condition, possibly from a prior generation where stress during pregnancy resulted in the birth on an HSP child.

It is amazing that stress can be so powerful that it can cause a human being to become a different person – that it can effect such a powerful change in a human being.  Violence and the threat of violence are bad enough under ordinary circumstance.  When they occur during pregnancy, a human being can be born with a variety of sensitivities as well as any number of genetic diseases.  That’s a lot of damage!  What causes the HSP trait is stress.  In a world of 7 billion people, reducing stress would seem to be a humane solution to the consequences of excess stress.