There exists an uncanny degree of similarity between the research on and the causes behind a person's handedness and their sexual orientation. As we will see, many of the same players are involved (see this related isocra.org article for a detailed review of the causes of orientation). The most striking difference, though, may be the current lack of political and social stigma behind handedness. For that difference it is useful to consider the research behind handedness, away from the biasing effects of politics and religion. Here we hope to illuminate the odd relationship between these two types of human orientations.

Contents:

• A History of the Sinister - Things weren't always this easy for the left hand.
• Causes of Left Handedness - The causes behind one human orientation aren't too different from another.
• Left Handed Genes - A genetic model that may explain handedness, or even some aspects of homosexuality.
• Conclusion - Sum up with satire.
• References

A History of the Sinister

While this article is meant to utilize the lack of stigma behind handedness, it should be kept in mind this was not always the case.

Left handedness has traveled a path similar to homosexuality. Like homosexuality, in classical greece, it seems being left-handed was not seen as a negative (see related isocrat.org article on the history of homosexuality). The Greek word for the left-handed was arisera, meaning fine or best, as in aristocrat (1). The Romans then became the dominant culture and they happened to call the pocket on the left side of their toga the sinus, which would lead to their word for left-handed (and our eventual synonym for nefarious), sinister. But it seems left-handedness fell out of favor at about the same time and in a similar way as homosexuality, with the rise of the Catholic Church.

The Psalms of the Bible, contain about 25 positive mentions of the right hand. In Matthew 25 the goats are kept of Jesus' left side and the sheep on the right: "Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels". Jesus sits at God's right hand (Mark 16:19), and so on. Simply, though not nearly as potent as the case of sexual orientation, the Biblical language against the left hand may have had an effect. The very english word left comes from the 12th century deriving from an old english word, lift, for weak or worthless (2), and left-handed came to be listed as synonymous in thesauruses for unskilled, equivocal and, of course, sinister (1).

Many superstitions grew up around left-handedness, as they did around sexuality. We throw salt over our left shoulder to ward off the demons that lurk on our left side. Evil spells were said to be cast by the left hand, and, even today, we only trust an oath with the right hand raised to God (3). Eventually, school children were harassed for being left-handed, even by teachers, even up to the last generation. They were often forced to try to convert to being right-handed, as many gays are now encouraged to convert to heterosexuality, but it left many with psychological damage, such as a stutter. One of such children describing a miserable left-handed childhood was a young Ben Franklin (4).

Even science once tried to uphold these biases, as it once did with homosexuality. In his 1946 book, The Master Hand, professor Blau describes left handedness being "nothing more than an expression of infantile negativism and falls into the same category as contrariness in feeding and elimination, retardation in speech, and general perverseness in so far as the infant with meager outlets can express it" (5). As with homosexuality, left-handedness was blamed by Blau on the parents, specifically the mother's "lack of love and attention". He also calls handedness a "choice" made by children to try to "criticize" their environment. The characterization of such an innate quality would sound oddly familiar to many a gay man and woman.

Even as late as the 1960's when college students were asked to associate words with left or right, they more often place left with words such as bad, profane, female, unclean, weak, death, ugly, and even, yes, homosexual, while right was associated with good, strong, male, life, and heterosexual (6) . While we may have dropped many of our anti-left-handed biases today, it is important to keep in mind this was not always the case and, at one time, not too long ago, the southpaws were more in the same boat as the homosexuals.

Causes Of Handedness

As is the case with sexual orientation, one of the first problems with studies on handed is the difficulty in pinning down who actually qualifies as left handed. Are they people who self-identify as left-handed, those who write with their left hand, or can the category include those who have that orientation but force themselves to write with their right hand? As Perelle et al. point out in their review, An International Study of Human Handedness: The Data (7):

there is no agreement among researchers as to who can be considered a left-handed person, what is the etiology of handedness, or what the proportion of left-handedness is in the world's population

By defining people by the actions they choose, we do find that just under 10% of the US population is left-handed and more men are left handed than women (8). In this way the demographics of handedness are strangely near those of people who participate in homosexual actions in both the prevalence and the fact that men are twice as likely to be homosexual (though about half that percentage self-Identify as homosexual) (9). With such a high occurrence of left-handedness, and no apparent benefit to choosing it over right handedness, one should expect a genetic role in the associated orientation. Unlike sexual orientation, though, this fact has been readily accepted without controversy. As Rief explains way back in 1939 (10):

“WHILE the occurrence of left and right handedness does not appear to conform to any simple Mendelian formula [a simple genetic mode of inheritance], the familial incidence of handedness rather definitely indicates a genetic basis.”

More recently, in a review by Orlebeke, 1996, we see this observation repeated with much supporting data (11). Simply, handedness clearly runs in families, has a genetic component, and no serious researcher disputes that today. However, finding the extent and mechanism of the genetic involvement has been a bit of a problem. In fact, much more is known about the genetics of human sexual orientation (see the related isocrat.org article).

Using twin studies, though, some interesting discoveries have been made. On the general topic, Sicotte et al., in 1999, did an excellent job of reviewing and compiling 28 studies, which represented almost 10,000 twin pairs, in “the largest meta-analysis of twins and singletons conducted to date"(12) . We will not, of course, go into each study separately here. They found, in part, for dizygotic twins (fraternal, not sharing the exact same genes) that if one twin were left-handed the other had a 9.4% chance of being left-handed themselves. This is about the same as the background, thus suggesting little upbringing effect, as the twins were raised together.

However, for monozygotic twins (twins who do share the nearly identical genetic codes), the other twin had a 14.9% chance of being gay. These same numbers for sexual orientation are about 30% for monozygotic twins, 15% for dizygotic twins, and 5% for the general public. So a genetic effect is seen, but significantly less than what is found for homosexuality.

What is also interesting is that, similar to what is seen in the Fraternal Birth Order Effect for gay men, left-handed twins also show a birth weight effect, as reported by Orlebeke et al. in a study of 1,700 twin pairs (11). They report “very low” birth weight correlated with left-handedness, and theorized that the “possibility that exposure to prenatal…hormones” made these children left-handed, as is theorized for some forms of same-sex sexual orientation. These finding were repeated by James et al. in 2002 (13). It should also be noted that same-sex twins were more often left-handed than opposite sex twins (14), again suggesting a hormonal or womb environment effect and a connection to sex-typical characteristics.

With only a 15% concordance in monozygotic twins, genes are not likely the whole story of the cause of handedness. It should be noted, however, that a completely genetic or otherwise biological cause of handedness is not nearly implausible, due to the fact that identical twins are not truly identical, even on a genetic level (see the related isocrat.org article). The additional causes may be items such as hormone exposure, immune response, and prenatal experience; nevertheless, as, the Sicotte et al. conclude (emphasis added):

Although the frequent occurrence of monozygotic twins who are discordant for handedness is clearly inconsistent with genetic models that would define right and left handedness as dominant or recessive traits, discordance among monozygotic twins does not automatically preclude straightforward inheritance of one or more genes that strongly influence handedness.

The genetic cause of handedness must be complicated, and a handful of studies bring to question the results of Sicotte, questioning the existence of any significant genetic cause. This is to be expected with such a small percentage of the population actually being left-handed. As with sexual orientation, some smaller studies, by probability alone will give negative results, and thus it is important for both topics to look at the entirety of data. For example Derom, was unable to find any significant difference between monozygotic and dizygotic twins using 808 twin pairs (15), and a similar finding was reported by Ross in 1999 with about 2,000 twin pairs (16).

There are many discordant identical twins who do not share their brother or sister’s handedness, and there are some interesting findings regarding the right-handed sibling (e.g. right-handed people with left-handed twins are abnormally strong in their handedness preference) (17). Still, discordance, gratefully, causes no one to rule out a strong genetic or biological effect or to claim left-handedness is a chosen lifestyle.

Left-Handed Genes

Figure 1. Right Shift Theory. Handedness distributions for a population of A) all mammals, B) Chimpanzees, C) Humans, and D) Humans with the theorized left handed genetic characteristics.

A prominent theory of left-handed genetics is one of a “right-shift” gene (or genes). Here the genetic influence does not make one left-handed; the gene makes nearly all of those holding it right handed, or leaves handedness to random processes in the fetus. It may be a simple Mendelian rule of inheritance, but with complicated outcomes. So handedness is determined by a completely random, normal distribution, but the genes might push that distribution's mean to a point where there may be no significant chance for left-handedness. The analogy to sexual orientation would be the evidence that shows developmental instability as a factor in homosexuality (see related isocrat.org article).

The history of this hypothesis is presented by its creator, Annett, in this review (18). This review has much more supporting information than we'll describe here, as the political implications of being left-handed aren't pressing. There’s also a book, describing this theory (19). Simply, handedness in animals is thought to be naturally in a normal probability distribution, meaning most animals have a certain handedness and a minority have stronger or weaker preference for the right or left hand. For humans that distribution is skewed to the right hand while, for other animals, they may be 50/50 left or right handed. This difference between humans and other animals was the impetus for the right-shift theory, as Annett explains:

…That is, the relative proportions of left-, mixed-, and right-handers in humans and nonhumans were consistent with a normal distribution, which was symmetrical about 0 for nonhumans but displaced slightly to the right for humans. This was the “aha!” experience on which the RS [right shift] theory was founded.

So it seems there’s something extra in humans (and chimpanzees) that moves the handedness distribution to the right, and it should be no surprise that, in some people, the mechanism that biases our handedness may be interrupted and we may return to the default distribution of mammal handedness.

There is a good amount of data to back this up regarding brain structure. In the review Annett goes over evidence involving topics from lesions in the brain to dyslexia, and so on. For a single bit of evidence from a more recent example, to add to Annett’s review, one could look at Geschwind (emphasis added) (20):

…cerebral asymmetry is strongly correlated with handedness, and handedness does have a significant genetic component… we examined the volumes of left and right cerebral cortex in a large cohort of aging identical and fraternal twins and explored their relationship to handedness. Cerebral lobar volumes had a major genetic component, indicating that genes play a large role in changes in brain volume that occur with aging. Shared environment, which likely represents in utero events, had about twice the effect on the left hemisphere as on the right, consistent with less genetic control over the left hemisphere. To test the major genetic models of handedness and cerebral asymmetry, twin pairs were divided into those with two right handers and those with at least one left hander (nonright handers). Genetic factors contributed twice the influence to left and right cerebral hemispheric volumes in right-handed twin pairs, suggesting a large decrement in genetic control of cerebral volumes in the nonright-handed twin pairs. This…is consistent with models postulating a right-hand_left-hemisphere-biasing genetic influence, a "right-shift" genotype that is lost in nonright handers,resulting in decreased cerebral asymmetry.

Also, in our chimp cousins, evidence of possible right shift genes have been found (21), just as much more research has been done on the causes of homosexuality in animals, rather than humans (see related isocrat.org article). We will not go into the data here but, as the abstract states:

We report evidence that hand preferences in chimpanzees are heritable, even among related individuals raised in different environments. Furthermore, we report that the degree of heritability is modified by factors associated with developmental instability, notably, offspring parity.

They also conclude that “The results…indicate that hand preferences in chimpanzees are probably genetically determined and most closely follow the predictions of the right shift model…” Chimps are about 2:1 right to left-handed, as compared human's 9:1 ratio. This leads researchers to believe a shared gene or set of genes will be found that cause this right-shift effect, but these genes have not yet been found and less seems to be known about their possible location than the possible location for genes affecting sexual orientation (see the related isocrat.org article).

I hate it when perversions are forced down my throat. I see them flaunting their aberrant lifestyles everywhere, on TV, at the office supply store; they even have they own day to celebrate their abnormality. Just the other day my child came home from school with a left-handed pair of scissors and told me his friend’s mom is left-handed! You people should just keep your personal failings to yourself and keep your left-handed propaganda out of our schools. It’s not the place for activism.

What prideful hubris. When my dad was a boy, they knew how to treat southies. Teachers would bind or smack the hand of those practicing such abnormal behaviors. These deviants should be grateful today we leave them live.

But no; this tiny militant minority has to push it. They demand my “tolerance” and “respect”, and yet won’t tolerate my views. Hypocrites. In the left wing media they’re all over. I’m constantly bombarded by attempts to convert my family towards their miserable choices. They’d have us believe we could all live lives just like Ned Flanders in some joy-filled left-handed lifestyle. Like it’s okay, natural, normal. What a lie.

But did you know left-handed people throughout history have been murderers and thieves? Science shows they are more likely to be schizophrenic (22, 23). They also more often develop immune diseases and migraines (24); they’re miserable people. Compared to normal people, their intellect suffers as well (24, 25, 26, 27). Left-handed people, no doubt by their “parenting” behaviors, are also more likely to produce children with mental retardation, and, of course, teach their children their same perversion (28). Children have the right to be raised in ideal family structures, and yet left-handers are allowed to procreate and adopt?!.

It’s a moral weakness, and we let left-handed and bi-handed people be authority figures to our children in our public schools, let alone become parents and marry?! Sure a few may, by some fluke, raise a passable child in their “families”, but we know scientifically, these kids are worse off, on average, mentally diminished with their schizophrenic “parents”. It’s simply not the ideal family makeup, to be sure, and we should promote the ideal. I’m not saying we should harm these innocent children in any way, of course, but treat them with pity, the poor victims, invalids, raised without right morals, by people selfish enough to raise them.

America has to start thinking of the children! (Not the left-handed children, though.) We should be outraged and stop worrying about the PC police, or about hurting feelings. They will make America into another Sodom, as the southies are even more likely to be gay (29, 30) (so I guess they aren't all that bad).

And, no, my aversion to left-handedness does NOT mean I’m secretly left handed! The idea of it makes me sick, no offence.

Now, to all you so afflicted by this moral weakness in my audience, let me say, actually, some of my very best friends are left-handed (or do you people prefer to be called Right Hand Restricted, RHR?). Like my friend Mary Stevens, do you know her? She went to a movie with me once and is left-handed; I thought you might know her... She told me all about how you live in your “community”, all about the left-handed lifestyle. But at least she knows she’s cursed with a detestable addiction.

Such good folks don’t flaunt handedness in our faces in public displays of “writing” or golfing. To watch them soldier on, regardless, scribbling on their right-handed ledgers, they humble me in their courage. They have a noble life of self-denial, sacrifice for their eternity of pleasure, unlike those lazy, debouched southies who mindlessly take handedness as a part of who they are and wallow in its many animal pleasures, like I can because I'm right handed.

Sure, being left-handed in itself isn’t really a sin; it’s just a part of a person that tempts them with evil, and we’re all tempted. This addiction isn’t evil or part of anyone, really, but CHOOSING to act on it is the very definition of sin. Abstention from using your hands altogether is a far more noble and preferable option. It doesn’t matter what harm comes or does not come from it; when you move your body in a certain way, in a certain geometry, do what I do with my right hand... Well, I’m telling you it’s against God’s law. I mean, please, you think God would be left handed, after separating us from the bi-handed animals of this world, into His image, into right-handedness? Still, I know the suffering you must feel at that (personally, I’m tempted to swear some times; I do feel your pain), but it’s the inarguable TRUTH.

While I love and respect all southpaws, I cannot condone that sin, and that puts my compassionate soul in a really difficult position. It’s tough love. I cannot sit idly by if anyone tries to normalize that perversion in my culture. There’s no debating it, but I hope you southies can understand. I must do what’s right, and, if I didn’t love southpaws and know what's best for their lives, I wouldn’t hurt them or my possible left-handed children (which I’ll not have as I raise children with morals).

I certainly would support anyone, though, when they decide to leave that deviant lifestyle. Keep that in mind, my left-handed readers. I know the life of those so addicted is filled with sadness and desolation--I’ll make sure of that--but THERE IS ANOTHER WAY! You can change! Studies show that upwards of 93% of southpaws, if they honestly want it and have enough faith and love of the Savior, can gain a normal right-handed orientation (Reference: Some guy’s web site that I read once and believe wholeheartedly. Dude, just trust me.).

In the meantime, struggle on and resist becoming an uncivil, militant southpaw activist, out there threatening the very sanctity of baseball. Their so-called “community” is nothing more than a bunch of one-dimensional creatures brought together by only their sick obsession with using their left hand, and the manipulations of Satan himself, whispering in their ears. They and their invisible demons only want to keep you from realizing your potential, and force their agenda into every American home, destroying the very fabric of society (somehow, but it will happen). Militant southies just hate society, and children, and America, and puppies.

Finally, don’t be taken in, my audience. Sure, the militant southies claim they want to be treated with legal parity, but they don’t really care about aptly-called “rights”. All they’re after is our endorsement of their twisted proclivities, to trick us into calling Evil “good” and Good “evil”. Don’t be blinded by talk of justice and equity--never let such marketing tools blind you--they’re only after the approval of corruption by righteous people like us.

I mean, who wouldn’t want the approval of people like us, right?

REFERENCES ::

1. Barsley, M.. The other hand: An investigation into the sinister history of left-handedness. Hawthorn Books, New York. (1966).

2. Barnhart, R.K.; Steinmetz, S.. Chambers Dictionary of Etymology. Chambers Harrap, New York. (1988).

3. Fincher, J.. Lefties: The Origins and Consequences of Being Left-Handed. Perigee Books, New York. (1980).

4. Barsley, M.. The other hand;: An investigation into the sinister history of left-handedness. Hawthorn Books, New, York. (1967).

5. Blau, A.. The Master Hand: A Study of the Origin and Meaning of Right and Left Sidedness and Its Relation to Personality and Language. Kessinger Publishing, New York. (1946).

6. Domhoff, G.W. But Why did They Sit on the King's Right in the First Place?. Psychoanalytic Review. vol. 56, pp. 586-596, (1969).

7. Perelle, I.; Ehrman, L. An International Study of Human Handedness: The Data. Behavior Genetics. vol. 24 (3), pp. 217-227, (1993).

8. Estevez-Gonzalez, A.; Garcia-Sanchez, C.; Junque, C. Neuropsychology of Left-Handedness: Current Knowledge. Revista de neurologia. vol. 24, pp. 515-522, (1996).

9. Kinsey, A.C.; Pomeroy, W.B.; Martin, C.E.. Sexual Behavior in the Human Male. W.B. Saunders, Philidelphia. (1948).

10. Rife, D. Handedness, with Special Reference to Twins. Genetics. vol. 25, pp. 178-186, (1939).

11. Orlebeke, J.; Knol, D.; Koopmans, J.; Boomsma, D.; Bleker, O. Left-Handedness in Twins: Genes or Environment?. Cortex. vol. 32 (3), pp. 479-490, (1996).

12. Sicotte, N.; Woods, R.; Mazziotta, J. Handedness in Twins: A Meta-Analysis. Laterality: Asymmetries of Body, Brain, and Cognition. vol. 4 (3), pp. 265-286, (1999).

13. James, W.; Orlebeke, J. Determinants of Handedness in Twins. Laterality: Asymmetries of Body, Brain, and Cognition. vol. 7 (4), pp. 301-307, (2002).

14. Carter-Saltzman, L.; Scarr-Salapatek, S.; Barker, W.B.; Katz, S. Left-handedness in twins: Incidence and patterns of performance in an adolescent sample. Behavior Genetics. vol. 6 (2), pp. 189-203, (1976).

15. Derom, C.; Thiery, E.; Vlietinck, R.; Loos, R.; Derom, R. Handedness in Twins According to Zygosity and Chorion Type: A Preliminary Report. Behavior Genetics. vol. 26 (4), pp. 407-408, (1996).

16. Ross, D.C.; Jaffe, J.; Collins, R.L.; Page, W.; Robinette, D. Handedness in the NAS/NRC twin study. Laterality. vol. 4 (3), pp. 257-264, (1999).

17. Gurd, J.; Schulz, J.; Cherkas, L.; Ebers, G. Hand Preference and Performance in 20 Pairs of Monozygotic Twins with Discordant Handedness. Cortex. vol. 42 (6), pp. 785-970, (2006).

18. Annett, M. Handedness and cerebral dominance: the right shift theory. Journal of Neuropsychiatry and Clinical Neurosciences. vol. 10 (4), pp. 459-469, (1998).

19. Annett, M.. Left, Right, Hand and Brain: The Right Shift Theory. L. Erlbaum Associates, London. (1985).

20. Geschwind, D.H.; Miller, B.L.; DeCarli, C.; Carmelli, D. Heritability of lobar brain volumes in twins supports genetic models of cerebral laterality and handedness. Proceedings of the National Academy of Science. vol. 99 (5), pp. 3176-3181, (2001).

21. Hopkins, W.D.; Dahl, J.F.; Pilcher, D. Genetic influence on the expression of hand preferences in chimpanzees (Pan troglodytes): evidence in support of the right-shift theory and developmental instability. Psychological Science. vol. 12 (4), pp. 299-303, (2001).

22. M.F., G.; Satz, P.; Smith, C.; L., N. Is There Atypical Handedness in Schizophrenia?. Journal of Abnormal Psychology. vol. 98 (1), pp. 57-61, (1989).

23. Cannon, M.; Byrne, M.; Cassidy, B.; Larkin, C.; Horgan, R.; Sheppard, N.P.; O'Callaghan, E. Prevalence and correlates of mixed-handedness in schizophrenia. Psychiatry Research. vol. 59, pp. 119-125, (1995).

24. Geschwind, N.; Behan, P. Left-Handedness: Association with Immune Disease, Migraine, and Developmental Learning Disorder. Proceedings of the National Academy of Science. vol. 79 (16), pp. 5097-5100, (1982).

25. Coren, S.; Halpern, D. Left-Handedness: A Marker for Decreased Survival Fitness. Psychological Bulletins. vol. 109 (1), pp. 90-106, (1991).

26. Soper, H.; Satz, P.; Orsini, D.; Van Gorp, W.; Green, M. Handedness Distribution in a Residential Population with Severe or Profound Mental Retardation. American journal of mental deficiency. vol. 92 (1), pp. 94-102, (1987).

27. Grouios, G.; Sakadami, N.; Poderi, A.; Alevriadou, A. Excess of non-right handedness among individuals with intellectual disability: experimental evidence and possible explanations. Journal of Intellectual Disability Research. vol. 43 (4), pp. 306-313, (1999).

28. Bradshaw-Mcanulty, G.; Hicks, R.; Kinsbourne, M. Pathological Left-Handedness and Familial Sinistrality in Relation to Degree of Mental Retardation. Brain Cognition. vol. 3 (4), pp. 349-356, (1984).

29. McCormick, C.M.; Witelson, S.F. A cognitive profile of homosexual men compared to heterosexual men and women. Psychoneuroendocrinology. vol. 16 (6), pp. 459-473, (1991).

30. Holtzen, D. Handedness and Sexual Orientation. Journal of Clinical Experimental Neuropsychology. vol. 16 (5), pp. 702-712, (1994).

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Created: 2008-12-11; Last Edited: 2008-12-11; (ID569)