Does left-handed sucking indicate ultimate left-handedness in a child?
March 5, 2015 6:23 PM   Subscribe

So, our beautiful 3mo baby daughter seems to strongly favor her left hand for thumb sucking. I'm right-handed, her mother is right-handed, almost everybody of our extended family (very large, 50+ first cousins just on my side alone) are right handed. That being said, my sister is a lefty. Question: is there any data regarding whether the hand a newborn / small infant uses to suck indicates future handedness? Nothing sinister in this question, just curious what we have in store.
posted by amorphatist to Grab Bag (33 answers total)
 
Well, anecdata? I am left handed, but I always sucked my right thumb. It's how I learned right from left, because I only ever sucked the right one.
posted by tomboko at 6:27 PM on March 5, 2015 [1 favorite]


I sucked my left thumb and am mostly dominant with my right hand, though I'm ambidextrous when I eat.
posted by brujita at 6:29 PM on March 5, 2015


Response by poster: As a corollary, I have no idea which thumb I sucked as a child (there's like three pictures of me before the age of five, and I'm in my thirties, I suppose I could question my mother tomorrow when the time zones align), so I'm curious how y'all know which thumb ye sucked as children?
posted by amorphatist at 6:33 PM on March 5, 2015


My youngest only sucks her left thumb. She is right handed. She is also 8 and still sucking that thumb. Try to switch baby over to a pacifier because you can take away a pacifier.
posted by myselfasme at 6:38 PM on March 5, 2015 [5 favorites]


I sucked my right thumb exclusively and am right handed.
posted by peanut_mcgillicuty at 6:41 PM on March 5, 2015


I'm curious how y'all know which thumb ye sucked as children?

Personally, I remember a lot of my childhood very clearly, especially early childhood. Also, I sucked my thumb a lot longer than that. - I don't know how old I was, but I remember the day I made the connection, "Oh! My RIGHT hand is the one with the sucking thumb! RIGHT! Got it!" and never mixed them up again.
posted by tomboko at 6:49 PM on March 5, 2015


Yeah, I sucked my right thumb. I'm left handed. Also keep in mind that left handedness is pretty variable. I do some things (write) left handed but not others (throw.) My aunt on the other hand might as well not even have a right hand.

"Nothing sinister in this question..." We see what you did there.
posted by sevenless at 6:49 PM on March 5, 2015 [11 favorites]


Nothing sinister in this question

I see what you did there.

I'd watch for grabbing. When she starts grabbing for things, if she's a lefty, she'll do so with her left hand. But I don't know that thumb sucking correlates. I'm a righty who sucked my left thumb (I remember because I did it embarrassingly long).
posted by chainsofreedom at 6:52 PM on March 5, 2015 [3 favorites]


Response by poster: Also keep in mind that left handedness is pretty variable. I do some things (write) left handed but not others (throw.) My aunt on the other hand might as well not even have a right hand.

Both me (righty) and my sister (lefty) are like your aunt. My left may as well be a vestigial organ, the only thing it can do is type on a keyboard, and that took years, *years* of effort. My left foot (apologies to Christie Brown) is even worse. I swear if I took a (soccer) penalty kick with my left, it would go 6 inches.
posted by amorphatist at 6:53 PM on March 5, 2015


My toddler daughter is a left hand two-finger sucker and I'm 90% sure she'll be right handed. But I have noticed she's ambidextrous while eating.

Interestingly it seems prenatal sucking shows an infant's preference
posted by bluesapphires at 7:01 PM on March 5, 2015


In my and my son's case it's actually the inverse, which makes a lot of sense. If you are busy sucking at the left hand/fingers, then you aren't practicing with it and getting stronger using it, so actually your right hand becomes your dominate hand. My 2 year old is an avid 2 finger sucker, of only his left hand. He is strongly right handed. I was the same way. My mom is a leftie though so it runs in my family and my older son (who didn't suck any fingers/thumbs) is fairly ambidexterous, so much so we had to just have him finally pick a hand, any hand when he was learning to write. So I'd bet that you will have a right hander, given the left thumb sucking preference.
posted by katers890 at 7:06 PM on March 5, 2015


I can't speak to thumb-sucking, but there may be some correlation between hair whorls and handedness.
posted by mogget at 7:07 PM on March 5, 2015


I'm a lefty, no recollection on what thumb I favored as a wee one in a majorly righty family though I do have a lefty uncle. Because left handedness has been hard to pin down, who knows. It has stayed steady at ten percent of the population though.
posted by KernalM at 7:10 PM on March 5, 2015


My daughter seemed to have a strong lefty preference in early gross and fine motor tasks. I was so thrilled because I think lefties tend to be more creative and take on interesting perspectives. However, now at age 4, it seems to be fading. Her Dad and I are right-handed so it could be our influence but I feel like in general, she's started favoring the right. So, keep an eye on it. Don't correct it but her handedness may change.
posted by amanda at 7:46 PM on March 5, 2015


Response by poster: Nothing sinister in this question

I see what you did there.


Oh, come on, I know it's cheesy, but as an exhausted new papa, you know that's fruit that can't be left unpicked!

I'd watch for grabbing. When she starts grabbing for things, if she's a lefty, she'll do so with her left hand.

Well, when we put her under The Claw today (named in honor of the U2 360 show), she seemed to switch depending upon which leg she was under. But that does make a lot of sense.

In my and my son's case it's actually the inverse, which makes a lot of sense. If you are busy sucking at the left hand/fingers, then you aren't practicing with it and getting stronger using it, so actually your right hand becomes your dominate hand.

Well, that's an interesting thought, I guess I would have previously assumed that handedness is innate (literally, you're born with it), does anybody have any pointers to any research on that topic? Does the science really know anything about where it comes from? I know there'll be a gang of ambi-turners chiming in here, but for me personally it feels utterly utterly innate. I mean, this left part of my body belongs to my dead twin or something.
posted by amorphatist at 7:46 PM on March 5, 2015


To add to the anecdata: I was a long-time thumb-sucker on the right hand. I am left-handed.
posted by Andrhia at 7:58 PM on March 5, 2015


When my daughter took up dancing, shortly after walking, it became obvious she was a lefty! It was so cute!
posted by Oyéah at 7:59 PM on March 5, 2015


More anecdata:

All my baby/toddler pictures until I was about 4 had me doing EVERYTHING with my left. I was pointing with my left, grabbing cake with my left, trying to doodle with a crayon with my left, poking my brother with my left (never was a thumb sucker though)....and I turned out right handed, though I am more ambidextrous than most people, but I'm not sure if that's innate or because playing lots of piano meant I couldn't be completely useless with my left hand. I am left footed though.
posted by astapasta24 at 8:22 PM on March 5, 2015 [1 favorite]


My daughter favored her left hand when she was a baby, so we thought she was going to be a leftie. She turned out to be ambi. Her softball coach was beyond thrilled to have a switch hitter.
posted by Ruki at 8:44 PM on March 5, 2015


The last time I looked at handedness research was over 20 years ago, but then it seemed to indicate that there was a genetic component but it was complex; that lefties generally are far more ambidextrous than most righties; and that it's best not to force anything. One of my good college friends was righthanded but wrote with the "inverted posture" that's normal for lefties (in which the writing hand hooks over the pen/pencil, rather than remaining under it). He participated in a study of right-handers who wrote like that, but I never found out whether the study produced any concrete results.

FWIW, I'm a lefty, quite ambidextrous except for writing, had an advantage learning the violin because my dominant hand did the fingering (but my other hand was sensitive enough for the bow), but according to my mom, I didn't suck my thumb.
posted by brianogilvie at 8:45 PM on March 5, 2015


More anecdata: I sucked my left thumb. I am right handed.
posted by His thoughts were red thoughts at 9:44 PM on March 5, 2015


Well, that's an interesting thought, I guess I would have previously assumed that handedness is innate (literally, you're born with it), does anybody have any pointers to any research on that topic?

Yes, there is evidence that it is genetic. Here is the paper.
posted by His thoughts were red thoughts at 9:46 PM on March 5, 2015


Hmmm, I write backhand(letters slanting left) and have gotten several comments from people observing me write that I do it "upside down ". No one tried to correct this aspect in school, though in general my handwriting has always been awful.
posted by brujita at 10:21 PM on March 5, 2015


I sucked my left index finger and am right handed. While sucking the finger I was generally doing a much more complicated tactile thing with my blankie with my right hand which might have been a tip off as to handedness.
posted by MillMan at 10:23 PM on March 5, 2015


I think the official wisdom is that one can see clear manifestations (ha) of handedness from the age of two. As parents (as opposed to momentarily testing paediatricians), one does see some stuff quite a bit earlier (if one looks for it). But 3 months - not so much. Be patient.
posted by Namlit at 1:10 AM on March 6, 2015


If you're interested in the topic of handedness, Dr. Chris McManus' Left Hand, Right Hand is one of the best popular science books I've ever read (imo.) He looks at bodily symmetry and asymmetry in general (as well as many other things!) which provides a context for his social and scientific examination of left-handedness. This is a quote from one of the reviews, which I wholeheartedly agree with: The author shows a fantastic breadth of knowledge as he covers not only handedness but also a wide range of subjects, including:
- Situs inversus - where the organs are reversed (i.e. a mirror image) but there is no increase in the likelihood of the person being left-handed
- Word associations - where typically 'good' words are associated with right and 'bad' words are associated with left
- Burial conventions - how different societies orientated their dead in different directions
- Symmetry of molecules - L-isomers and D-isomers - and how a different orientation can have a radical effect on the nature of the molecule
- A collection of left-handed myths (and explanations)
- An analysis of which side of the road countries drive on
- And much, much more
This is popular science writing at its very best and the result is one of the best popular science books I have ever read.

posted by glasseyes at 2:38 AM on March 6, 2015 [2 favorites]


I'm curious how y'all know which thumb ye sucked as children?

Ask your (ex?)thumb-sucking friends in private how come they know
posted by glasseyes at 2:41 AM on March 6, 2015 [1 favorite]


Don't know about thin-sucking, but ALL of my grandparents, parents, parents' siblings and my own siblings, plus 55 of my 56 cousins are right-handed: in our large extended family, there's just left-handed me and that one cousin.

There was a time when I wrote with my hand hooked around; to make it really weird, I also had whatever I was writing on literally upside-down as I wrote on it. I didn't start out that way: it was the end result of battling a teacher who, back in those dark ages, tried (but failed!) to force me into switching to right-handed. Eventually I went back to the 'proper' way of holding my pencils and paper, but that damn teacher warped me for a few years. Nowadays, I am, as I've always been, a committed lefty; my writing (both printing and script) is clean and clearer than the majority of people's, and slants slightly to the right.

For some reason, the thing that makes people freak out a bit is chopsticks: I've used them since I was a kid, and people can't seem to figure out how --- like what, it's some kind of miracle just because I'm a lefty?!? One of my coworkers, a Chinese guy, laughs and says I use them better that some of his relatives.
posted by easily confused at 2:47 AM on March 6, 2015


One of my kids sucked her right thumb and is a hugely dominant leftie adult. Her right hand is almost useless. She is incredibly scientific, analytical, and almost robotic in her response to emotion.

One of my kids used a pacifier and has almost 100% complete ambidextrous abilities. He's easily frustrated, sort of good at almost everything, the kid who gets B's without trying, but not a master in anything. His empathy is so strong that he connects with everyone everywhere and is often exhausted by this.

Third kid never had any oral thing and she's a strong rightie who's wildly creative. She loses track of time because she's watching pretty clouds.

I have no idea what any of this means.
posted by kinetic at 3:09 AM on March 6, 2015 [2 favorites]


Anecdotal, but I sucked my left thumb and I'm most definitely right handed. I know it's the left thumb I sucked because I, uh, still suck it when I'm tired.
posted by lydhre at 3:41 AM on March 6, 2015 [1 favorite]


I sucked both. Now I'm right handed (but I throw with my left).

I always liked the right one better though. How can I remember? I just tried both of them!
posted by mgrrl at 4:19 AM on March 6, 2015


So to flip around what I said before to take into account the genetic component. You may still have a predisposition to stick your non-dominant hand into your mouth because you want to use and it's easier to use the dominant hand to do stuff with, so if you are going to incapacitate a hand for comfort only, best to use the "bad" one. So that works for strongly handed people. For people who were perhaps more genetically ambidexterous, you may see a shift towards a more specific handedness caused by finger/thumb sucking due to practice effects. That's sort of what happened to me with footedness. I never participated in sports that required/promoted a strong footedness (soccer, etc) until I was an adult and started taekwondo, which strongly uses both feet. Now I use both easily and with equal skill even though I'm quite strongly right handed.

Of course I'm just completely making this up based on the anecdota in my life, but sounds plausible at least. Really the answer is that it's too early to see handedness, especially if you've got a non strongly handed kid. My oldest is almost 6 and we can't really say what he is, and my youngest is almost 3 and strongly right handed, but that wasn't clear until he was over 1 year old.
posted by katers890 at 6:26 AM on March 6, 2015


lefties generally are far more ambidextrous than most righties

Given how much stuff is designed for righties, that's not too surprising. Righties might be more ambidextrous if lots of stuff were designed for lefties.

I'm a hooking right-hander too, as are my husband and sister. I'd be interested in hearing about studies about other freaks like us.
posted by Anne Neville at 6:34 AM on March 6, 2015 [1 favorite]


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