Is being left- or right-handed genetic?

8 Comments

1. - Ken - July 12, 2020 Reply

   nice first vid Mike, very insightful (the 2nd was excellent as well). even w/ identical genetic twins, once the fertilized egg splits into zygotes, each becomes an individual and all external & internal things will affect each slightly differently…and so from that point of separation/individualization/creation each immediately/instantaneously begins the process of differentiation/becoming unique from the other/becoming one’s own self. though w/ identical twins these differences between individuals are less noticeable than they are normally between non-identical twin individuals.

   i think there’s at least a general tendency for more lefties and ambi-lefty biased individuals to be allowed to flourish & exist/live-out-their lives as well/as fully as is possible if there are other lefties/lefty-ambi’s or maybe righty ambi’s in one’s immediate and/or extended family. i speak from experience being left-handed-biased ambidextrous. i have a female cousin ~ my age who says she’s O neg and we’ve always gotten along well. there’s so much left-brain-hemisphere/right-hand dominant cultural and individual bias against being/living firmly as a lefty or lefty oriented/preferred/organized individual (not to mention all this says against the lack/loss of creativity, tolerance, “diversity” (in a non-racial sense), freedom and un-forced choice among so many other things.

   i think and i think studies show this: that generally most people have a natural brain/body bicameral usage preference that develops as one’s brain and body are organizing/grow into it’s self/natural potential and bias/leaning. the fact is: in reality nothing/no-thing is equal in any respect ever…so to think handedness preference should be exactly even or absolutely equal in anyone is just not true. there is always going to be a bias/preference/leaning and so on and likely for very good reasons.

   in Psychology studies, there’s evidence that shows that as children/siblings are born (regarding birth order and especially i think those born rather close year-wise to each other) there are open “niches” in a sense that can be filled. first born, if the parent are okay w/ this, can easily become a good student/bookish, the leader based on being first/oldest, likely more mature and so on…and the 2nd born (often may take/step into a completely open “niche” way/type of living) may choose to be a hands-on learning person…again, if this suits the individual and the parents allow/accept this. this type of non-competitional development is quite common. i think people would get along better if they understood these dynamics, saw the value in of both of these types of learning and the societal needs for both types and more along w/ creativity and the importance of allowing self-individualization, so all can self-optimize and all the problems of the adult world be solved and dealt w/ as well as possible. identical twins may have a slight added tendency to prefer/develop opposite brain hemisphere usage naturally for similar very subtle reasons.

   maybe left-handed bias/preference in RhD negs exists to a larger extent than the rest of the populaton because we were already significantly different from the start and being even more different still was not such a big deal…it’s just one more oddity among so many…or maybe there’s a heart-feeling/right-brain hem’ & left-side body usage bias/creativity bias and more that’s somehow related and/or derives from being RhD negative generally. it would be nice to see a list of RhD negs who are lefty/lefty-biased ambi or righty-biased ambi. i think this/these human created systems/us-we/the societies that humans have created are dying from the lack of using the things the other/shunned half of the human brain (the right brain hemisphere) is best at doing. i seek a good balance between the two hem’s…not a war…and not the seeming to me, lobotomization of the qualities of the right hem’ because the left-hem’ has a problem w/ intolerance and perspective/depth/art/creativity and similar such things. – differences make a difference – regardless of where, when & why they happened…some/many cannot accept differences or much that is true/truthful/truth seeking/truth oriented/honest and so on …. – perhaps the brains/this differences among the brains (on another level) are framing/contextualizing/shaping it all in very real sense/way –

   i didn’t decide completely i was lefty-biased ambi until i was in my late teenage years, w/ much needed left-handed only and always going forward hormone balancing actions (although i always brush my teeth w/ my left hand unless it’s severely hurt for some reason of course…shot pool lefty…as i said before: chose to write w/ my right hand a age 6 because it was practical and i was being forced to use my right hand to eat w/ as well at this time and into my 8th year….i eat w/ my left hand now/still preferentially. my father would was always against me learning how to do seemingly anything w/ my left hand, which is insane beyond my natural bias since i have two well functioning hands & arms and all ya know?). 4 things i noticed later in life about being lefty-biased & ambidextrous: i will shoot rifles right handed, since most are made this way; but using one of my father’s pistols at a shooting range (~ 30 years ago) there was an unbusted “clay pidgeon”/ceramic disc laying 25-30 feet away on the sand berm. my father had been aiming his pistol at it and firing and kept missing it. he’s righty-biased strongly…and then i got my chance…using my left hand, i just slowly brought the gun up and w/out aiming through the gun site just pulled the trigger when i thought/felt my aim was good and blew the disc all-apart. in hindsight/when thinking back on this subject: lefties…in the mid ’90’s i realized i tended to get along well w/ all of the lefties i knew (or my lefty-biased ambi/”whatever hand is handiest” likely O neg grandfather). we could communicate well w/ each other regardless of age, IQ, social status, sex, business relationship…in short/in sum, we communicated very well and we were often the only one’s who were able to understand or w/ whom i was able to talk about or mention certain things. there’s much truth and real value in all this. it’s deep and very meaningful. two other things: i’ve arm wrestled a lot over the years, because i’m good at it…for most right-handed biased guys, their left arm was their strongest arm. for me, being lefty-biased ambi, my right arm is stronger in general (one’s fine motor skills seem to be very much linked to which hand one prefers to use most often/ambi’s can go beyond this being able to use which ever hand suits the task or whatever best generally…and then there are those 2 handed situations and actions). these characteristics also became obvious when i was pulling back on my brother’s right-handed shooting compound bow (there’s a lot of force required to reach the arrow shooting position) and i realized i really couldn’t do it the way it was designed to be used…ie holding the bow shaft w/ my left hand while pulling back the cord w/ my right hand…but, when i switched to holding the bow w/ my right and pulling back w/ my left, i was able to pull the cord back to the arrow shooting position w/ ease. my brother could not pull the bow cord back switching to lefty, neither one of us is weak. so, there are real differences here: it’s not just in the brain, the blood, the genes…but it/this bias also becomes manifest in one’s body as a whole overall. it just takes some time i guess.

• Gary Talbot September 12, 2020 Reply

  I am reading it, as the only confirmed left hander on either side of the family in about 130 years.
  My son is right handed.

2. Richard July 12, 2020 Reply

   See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2666081/ for more info. on left-handedness.

   As a right hander, I have always disliked the derogatory connotations made towards lefties, such as “sinister” and “cack handed”…not to mention the practice of forcing a person to do something that is contrary to their biological make-up (i.e. forcing lefties to use the right hand as dominant.)

   Rh negs have been the victims of such slurs as well.

3. - Ken - July 13, 2020 Reply

   some comments & thoughts of mine on this study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2666081/

   this is a heavily math-minded left-brain hemisphere leaning study imo…it’s seeking/the authors are seeking to find what determines why/how/when/where one becomes left-handed. they seek determinism…what absolutely-perfectly explains why lefties exist…the why/if & how their percentages change over time and in different populations.

   the study is simplified imo, since it only really focuses on left or right hand preferred usage and does not consider/mention ambidexteriy much in any way at all. i’ve lived through this process from birth. i remember and understand it all very well & have studied and considered it for years at length and in depth. to not mostly discuss how human brains develop and grow from birth through to about age 6 is a major flaw in the focus of this study. i think they may have avoided these questions because it’s not their area of expertise. one can look for the underlying causes for left hand preference all one wants, but to apparently start w/ an unstated premise that being lefty is partly hereditary and all the other reasons for it are likely some flaw in development and/or a pathology is just more of the same old right-hand left-brain hem’ is superior crap i’ve bumped into my whole life mostly. i’ve stated as much here many times over the past 2 months. it’s nothing new for me. same problems…same issues…blatant myopathy – and an unwillingness to acknowledge an actual hatred of part of one’s own self…the other half of one’s own brain & mind. i deal w/ it. if the majority of humanity can’t deal w/ it’s own internal mental issues, well then – once again – i say: humanity’s doomed. for me: i was a very healthy child and a strong child, was extremely precocious and matured biologically much sooner than my peers. have always, since even before puberty, had a very high t-count level. i still do. studies i’ve read say high t-count men tend to be healthier than lower t-count men generally…at lower risk for lung cancer and more, but tend to be bigger risk takers…heh yeah, what’s the saying: that it took balls to do that or you’ve got a pair…anyway…there seem to be different kinds of testosterone…some (one type? and perhaps other things/there seems to be a genetic link here) seem to make some men go bald…others do not, or at least they haven’t done that w/ me so far.

   – once again my comments: i see this all as largely a brain hemispheric preference/bias/dominance issue…i seek/try to use both sides of my brain well. i seek balance between my two brain hemispheres and things w/in myself…and i’m always seeking to live a satisfying life, always. –

   “If there really are two distinct groups of left-handers, one of pathological origin due to low birth weight, and another of familial origin, then there should be a tendency for bimodality in the birth weight distribution of left-handers. This predicts a lower overall birth weight for left-handers and a greater variance in birth weight for left-handed as opposed to right-handed individuals that should be investigated.
   Although developmental and perinatal problems can be partly due to environmental conditions, they are significantly heritable (e.g. Cai et al. (2007) for birth weight or Moller & Thornhill (1997) for developmental instability), indicating a genetic contribution. Their link with left-handedness therefore represents a negative selection pressure.”

   “determinism”…no choice…i’m repelled by such discussions/the idea/the concept. the old box the mind up or put a box over the young and gullible student’s head (in philosophy and other mental gymnastic scholastic studies) and then proceed to beat the sh*t-outta-‘em w/ a stick. that’s my impression of the arrogant and mostly useless field of Philosophy now. yeah, i’m a lover of wisdom…but not of the fools & asses who try to enslave me or any others w/ their tortuous and neutered so called logic and reasonings.

   “The fact that the polymorphism of handedness is maintained in all human populations suggests that handedness is not a neutral trait, and that some selective forces are maintaining this diversity. Directional selection, if acting alone, would lead to the fixation of the advantageous morph, and eliminate the polymorphism. ”

   more absolute horse-sh*t theorizing w/ regards to me and my life experiences (see the next quote below). the insane need to make “right”-handedness – THE ONLY WAY – to be/exist is as i’ve said: one half of the brain/the left side (seemingly to me mostly) has a problem w/ intolerance, w/ differences (it seems to be scared and threatened by them…by things it doesn’t and will not willingly want to understand). the left hem’ wants to lobotomize the right-side/it’s other different half…and so as i’ve said humanity is doomed. the vision of the left-side-brain-hemisphere is limited to a machined/numerical vision of things largely and it’s unable & unwilling to see or accept any other vision/future/or reality of things now – & going forward. numbers suffice, human values are secondary and dustbin destined.

   “For males, it is clearly established that height is correlated with reproductive success (Pawlowski et al. 2000; Mueller & Mazur 2001; Nettle 2002a). Coren et al. (1986) also showed that an association between delay in physical maturation (based on the onset of secondary sexual characteristic, age of menarche and relative body size) and left-handedness (see Eaton et al. (1996) for contradictory results). A delay in sexual maturity could also have an influence on reproductive success and thus lead to some fitness cost for left-handers. Further investigations are needed to quantify the influence of this factor.”

   FINALLY SOME GOOD THINGS ARE SAID:
   “Left-handers have indeed smaller asymmetries in hand skills than right-handers (Peters 1989; Curt et al. 1992; Judge & Stirling 2003) and are less lateralized in language dominance (Steinmetz et al. 1991). Smaller right–left differences as well as higher intermanual coordination in left-handers may be due to greater control of both hemispheres. …. some studies point to better interhemispheric transfer in non-right-handers …”

   “A larger corpus callosum has also been reported to be associated with superior verbal fluency (Hines et al. 1992) or to confer advantages in some forms of memory (Christman & Propper 2001); two advantages from which left-handers could benefit.”

   “Creativity has also been reported to be linked with left-handedness (Newland 1981), more specifically in men (Coren 1995). The proportion of left-handers also appeared to be greater in gifted children (IQ>131) than in non-gifted children (Hicks & Dusek 1980), but the importance of this effect at the population level remains to be quantified, owing to the low proportion of gifted children. ”

   “Another important benefit of left-handedness could be represented by a strategic advantage of left-handers in sports: ”

   – i says: focus on the brain damn-it –

   “Although 97 per cent of right-handers demonstrate predominant left hemisphere language localization, only 60 per cent of left-handers demonstrate left hemisphere language dominance, 30 per cent show bihemispheric language and approximately 10 per cent show right hemisphere language (Geschwind 1970; Annett 1985). Precise characterization of categories of left-hander should help the understanding of the evolution of handedness.”

• - Ken - July 14, 2020 Reply

  sure – there are lots of environmental factors that affect which hand one chooses to use for a specific task, w/ a specific thing or whatever…people, relatives, parents, cultural norms, the commonly found right-hand/right-side bias in things produced – designed for the 70% or so of people who are largely/mostly oriented/body & brain-wise wired/built (designed) this way. seems to me: the hand/arm with which one has the most dexterity, will likely be the one that one chooses to use for most/nearly all tasks requiring the most hand-eye skill/coordination. the favored hand will often be used with those tasks requiring just one hand, and the favored hand/body side will most often be used to do the more important part of 2 hand actions if possible. for those who are not largely ambidextrous, the most dexterous hand & same body side usage (assuming lack of injury, missing or overly damaged body parts and so on) is usually easy to see. for those who are ambi’, the bias is often less obvious. environmental factors – things external affect how many lefties are noticeable in any society.

  being part of another minority – those w/ a left-hand bias to at least some notable degree – i claim, at least for me, that my left-hand bias is not a conscious choice i made – it’s how i was created/born/brain & body wired-organized & so on. i expect most – nearly all right-hand/right body side preferring individuals would agree with me about preferred hand usage – using the most dexterous hand for the most challenging tasks most often when able. most people use both hands for many things constantly. there is usually a preference – a bias – a favored hand etc…. from my pov, handedness – one’s body/brain bias or general ambidexterity should not be a big deal. i’ve learned to live well w/ what i am. there is a genetic aspect to hand bias. it doesn’t appear to be large but it is evidenced by the fact that lefty-biased people are more common in families that already have lefty-leaners in them (and apparently by the study above which shows left-handers being slightly more common among identical twins than they should be if genetics was not involved at all). tolerance through to intolerance, affects what others see…it does not really change the actual/natural bias a person has, but it may surely FORCE opposite body parts to be used – while concurrently weakening those one would’ve naturally chosen to use.

  i do think there may be more lefties and ambi’s in the RhD neg group than in the general pop’. i can only really speak for O negs…but: including myself, a passed-on friend and my close relatives i’d say we O negs are/were either lefty or ambi – everyone/every person…2 lefties perhaps (one may be O+) and possllby 4 ambi’s (at least 2 w/ a lefty-bias). oh well, i’ve typed way more than enough lately for now. find the good in people – what each does well – and don’t exploit other’s for their weaknesses. – live/learn/seek to improve – one’s self & things – & seek to live a satisfying life always –

4. Robin Pryha July 14, 2020 Reply

   Everything is genetic! If a parent RH neg and ambidextrous or left handed, well the odds are the odds! Ok mike my question….I remember everything g, it’s weird but it’s up there…Leonardo can Vinci wrote mirror…backwords…so I’m right handed…both parents left handed, one claims he was forced to write right handed by nuns and was hit on left hand with ruler…I took a test…only left handed person’s can read as well backwards( mirtor) reading fast…I took test it was as easy as reading normal! Another test is left right brain test….I think like myself RH negs will test equal…it’s an app! I’m super smart with science yet I want write draw…I get quantum pbysics, yet I’m knitting a blanket…love art, love science…I can guess…RH begs are using both hemispheres…this makes us unique, and possibly do better on is tests…was sad for drunk took ambien, 3am got 122 is score when I was out to lunch…just a thought!

5. Robin July 14, 2020 Reply

   Everything is genetic! If a parent RH neg and ambidextrous or left handed, well the odds are the odds! Ok mike my question….I remember everything good memory it’s weird but it’s up there…Leonardo daVinci wrote mirror…backwords…so I’m right handed…both parents left handed, one claims he was forced to write left handed by nuns and was hit on right hand with ruler…I took a test…only left handed person’s can read well backwards( mirror) reading fast…I took test it was as easy as reading normal! Another test is left right brain test….I think like myself RH negs will test equal…it’s an app! I’m super smart with science yet I want write poetry and draw…I get quantum pbysics, yet I’m knitting a blanket…love art, love science…I can guess…RH negs are using both hemispheres…this makes us unique, and possibly do better on is tests…was sad for drunk took ambien, 3am got 122 is score when I was out to lunch…just a thought!

6. Vivella September 18, 2020 Reply

   My mother was the only left-handed child in her family. I am the only left-handed of her children. I am BRH neg. I am quite ambidextrous but am still left hand dominant. I only do ironing with my right hand, I eat with the utensils in the proper way like right handed people (fork on the left, knife on the right), but as soon as I have to use only one utensil, I have to use the left hand only. I am very artistic and creative, I paint art etc but i am very logical as well, more so than many, maybe creativity has something to do with finding solutions to practical issues? My son is left handed and is AB RH neg. My daughter is right handed and has A positive blood like her father, who is also left handed. So 3 of us out of 4 are left handed. Several people in my extended family including my son, myself, my mother, aunt and some cousins have negative blood types, and my son is not the only AB neg in the extended family..all from my mother’s side. My mother used to be a dressmaker when she was alive and had to have a special left handed scissors made for her, to be able to cut fabric comfortably. I took great care to make sure my son had left handed scissors when he started school. There are so many small things people are unaware of regarding being lefthanded, and how we struggle with basic things because most items are made for right handers. I have to be careful what kind of potato peelers I buy, hand blenders, etc often have the handle in the wrong place for me. Writing in school with a fountain pen many years ago was an issue, the work would smudge as the ink was wet, so I used to put a piece of blotting paper over my writing as I went along, for my hand to lean on and I used to turn the paper I was writing on, at a slant. Small things that right handers take for granted, we left handerss get used to doing it differently for ourselves. Both my mother and my ex husband were beaten and forced at school to write with their right hands.

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