Gifted Issues Discussion homepage Forums Parenting and Advocacy Are siblings usually gifted also?

Hi there! I was curious to know if people who have one gifted child have others as well. My DS7 is PG and we also have a DS who just turned 3. He seems very smart but in a much different way than his older brother. DS7 is a perfectionist and a talker and it is easy to see his giftedness. DS3 is very laid back, silly and really can't be bothered with most things. I think that their different outward personalities make them seem more different than they actually are. So, anyway, just curious if siblings are usually gifted as well... I want to be prepared;-) I've also read that siblings are usually within 10 IQ points of eachother - is that anyone's personal experience?

Thanks so much for any comments!!!

I've read the same - that siblings are typically within 10 or so points of each other.

Honestly, I don't think that's the case with my two... my son is at least highly gifted (hard to say with his 2e-ness) and picks things up the very first time he learns about them... while my daughter... she's a good student, meets the school's goals, but doesn't really seem to go much beyond that, and often has a difficult time learning new things. I'd say she's maybe mildly gifted.

I believe that the place I've heard that 10 point rule come from is the Gifted Development Center. I've never seen any actual studies done to support this. The GDC, I believe, came up with that based on what they see with kids whose parents bring them in for testing. I'd have to expect that there is some bias there, though, in that they are quite expensive and something like 84% of the kids they assess wind up with at least mildly gifted IQ scores. Thus, I'd suspect that parents who are willing and able to spend $1-2K on testing for multiple kids are pretty darn sure before putting out the money skewing the results toward more of the kids they test being gifted. This is, of course, just my own conjecture.

I'd be curious to see if there were actual studies done separate from a self selected group like the GDC has.

eta: this is all anecdote as well, but this issue was discussed a few months ago here as well with various people chiming in as to their experiences with IQ similarity or variability among their own kids: http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/142624/1.html

Is that the only place that stat comes from? If so, I'd have to agree with Cricket2--I'd hardly consider it reliable, for those reasons. Still, we do know that intelligence is highly heritable.

To the OP--I'd caution you to be careful about underestimating a second child who presents differently, First kids tend to have certain personality traits that align with a traditional concept of giftedness, and may tend towards more outward achievement, while laterborns may decide to take on different roles but be just as bright. Also, your second is very young. I have revised my estimates of my children's relative giftedness a fair bit over time, and may do so again.

I'll agree with ultramarina too as there is good indication that intelligence is pretty heritable, but genes are also pretty complex and most families have some variety in a lot of things from curly/straight hair and height (also fairly strongly heritable) to IQ. Depending on how diverse the genes coming into play are, there may be more or less variability among the family members.

Also, in agreeing w/ ultramarina, family roles and personality can certainly impact whether a child outwardly presents as gifted. My dd14 is more obvious about her giftedness than my dd12 due to a number of factors including a greater 2e thing going with dd12, personality, and perhaps other things.

I think the place that I read that 10 IQ point statistic is in Dr Ruf's 5 levels book. (I think I've heard her say it during one of her presentations also). I can't find my copy right now to check to be sure.

ultramarina - I totally agree with you about not underestimating my second child. That is why I wrote the post. (Maybe I just needed to hear someone say that my two kids can both be gifted but in different ways). My first experience with a gifted child is the one I've had with my first son. As I stated before, he is an overachieving perfectionist. My second son is just so much different from him, but still very bright.

Twins and Siblings: Concordance for School-Age Mental Development
Ronald S. Wilson
Child Development
Vol. 48, No. 1 (Mar., 1977), pp. 211-216


However, they also did some more in-depth analysis of twin-sibling sets (comparing a pair of twins with a non-twin sibling).

Wasn't there some research regarding the X chromosome and general intelligence recently?

Actually the GDC's standard is 13 points for 70% of siblings. According to them 100% is withing 30 points, unless you are dealing with 2E issues.

If one sibling is gifted the other is too. Not necessarily. If you have a MG child of 135IQ the sibling could be at 122IQ and not gifted. So at the lower ranges of the gifted scale maybe it is not so. I highly doubt though that if you have a PG child the sibling would be average although there could be 2E issues that would depress scores making it seem that way.

And I agree to not compare. Here is my story.

DS5.3 tested PG and has always seemed PG academically. H was copying books on the computer right after he turned 3 and started writing his own stories shortly after. Noone taught him how to spell, he just new. He has always gotten up in the morning and worked in his room writing. all he wants to do is write and learn. he past 2 months he has taught himself all about geography. He knows he name of every single country in the world looking at a map with no names of it. Learned about all the mountains, population, countries size etc. He is obsessed to say the least. He is doing long division and multiplication. It is ALL about academics.

Now jump to DS3.2. Although he loves books and could spend hours reading, ask me to do workbooks with him, reads easy sight word readers and knows some simple addition up to 10 he is no way near as interested and obsessed with it like his brother was/is.

The difference in the 2 is the thinking process. DS3's abstract thinking ability is remarkable, his attention to detail seen in various formats or just out and about. Both have always been very observant but DS3 is still more. An example, a couple of months ago DS3 was sitting staring at a picture and asked what something was. I said it is water. Like a beach, and water. He kept staring and asked but what was IN that water then. He gets very obsessed with things like this. DS5 was right there and I could see he looked at the picture clueless to why anybody would ask a question like that. I am sure something like that never crossed his mind.

So completely different children. We might have DS3 tested in a couple of years, or actually we will because of some of his sensory/emotional sensitivities. It will be interesting to see what the difference in IQ will be.

Maybe +/- 10 points is typical, but we're talking about children who are, by nature, exceptional, no?

You couldn't prove that rule by my family. I'm the third of four boys, and I got the "smart one" shingle hung around my neck pretty early on. Both of my older brothers had the opportunity to capture that one first, but nobody noticed anything unusual in them, nor in the one who came after me.

The younger one has some personality red-flags for being an unidentified giftie, though... and since at least two generations before us went completely under the radar (mom's story is a classic of underachieving rebellion), it's worth looking at.

My four are all gifted, but definitely express it differently. The youngest is very typical of the youngest child - charming, empathetic, social, and just a tad lazy (or at least not as driven). I've definitely had teachers say (verbatim), "Wow, I forget how smart is he" because - he's a goofball, he's such a social butterfly, all he talks about is sports, etc... this is usually after they see some test scores! Although he hasn't had IQ testing, he rocks pretty much every test he's had, from the EXPLORE to the CogAT. Each of my kids was different- the oldest, PG perfectionist, the second very verbal people pleaser, the quiet mathy one, and the baby. TRY not label them. I think dh's brother still has his hackles up about dh being "the smart one" (his advanced engineering degrees and great professional success notwithstanding, BIL is still viewed as the social one, not the smart one, by his clueless family).

Our kids are yet to be tested ... we don't need it at this point but will go that route if we need to in the future ... but I'm pretty sure they are both in the gifted range. The older one I'm guessing will be somewhere around where I was as a kid (140-145) and the younger one, while he's got more challenges to overcome, I believe is higher than that but it will be really hard to do any accurate testing. The boys are 19 months apart.

My older sister and I are almost 6 years apart and while I was the one doing all the funky gifted stuff, she's probably higher average. She is smart, no doubts ... but there are times when I feel like she needs a good smack over her head with a frying pan to get that light bulb going! (and it's NOT because of siblings rivalry! :)). ... which makes me wonder if maybe age difference comes into play somewhere in this too? ... just thinking out loud.

I think that this is where the GDC is usually quoted re this issue: http://www.gifteddevelopment.com/What_is_Gifted/learned.htm
A couple other links I could find about siblings and IQ:
http://www.psychologicalscience.org...lings-closer-in-age-have-similar-iq.html

http://www.iq-tests.eu/iq-test-Development-420.html
Okay, number crunchers, can we figure out what a .6 correlation, which I believe constitutes a moderate correlation if I recall correctly from stats, would likely mean in terms of how many IQ points apart siblings would be on average?

I don't think we can. You could conceivably have two data sets with identical distributions and a .6 correlation. (Or a 1.0 correlation, or no correlation at all.)

If you assume for the sake of argument that Kid1 in each family lies precisely at the center of the sibling-cohort IQ distribution, 68% of the other kids in the family will fall within one standard deviation of Kid1's score, with most of those a good deal closer. A sibling cohort may or may not have an SD of 15, and it's possible that each of two kids would be outliers at opposite extremes. But if you had a thousand-kid family so the statistics meant something, most of the kids would fall into the same general IQ range. So we shouldn't be surprised when kids in a much smaller family often do, too. (Nor should we be surprised when they don't, because statistics don't tell you anything useful about a specific individual.)

I have 2 DSs, each from a different marriage. DS24 was identified as gifted when we moved to NC (VT doesn't have state laws concerning gifted programs) when he was in the fifth grade. We did not have him tested, though he did take an SAT in 7th grade through Duke Tip.

My DS11 was identified as GT in first grade but honestly, because he is so completely different from his DSB, both in personality and strengths, we were surprised. But we always seem to be surprised by our DS11, to a fault. We've not had him tested either but he recently took the Explore Test and did very well.

I read something about this... there are something like 140 (can't find it anywhere I but I think that's what I read) genes associated with cognition on the X, and not nearly as many on the Y. Girls have spares Xs and boys don't, which is why girls are less extreme (the two Xs balance each other out). So statistically (supposedly) there are more boys with extremely high and extremely low IQs than girls... more boys diagnosed with autism, ADHD, etc etc.

Also worth mulling over is the idea that because of this link, much of cognition comes from the mother. Not sure how true this is... there are lots of gifted dads out there who have passed down their talents to their kids... but supposedly for a son, because he only gets one X, if mom is gifted, he's more likely to be as well (unless... mom has a strong X and a weak and he gets her weak).

(Have I just revealed my layperson's ignorance about genetics? ;p )

EDIT - just did a quick google:

http://hmg.oxfordjournals.org/content/14/suppl_1/R27.full

"X-linked genes play a disproportionate role in the development of human intelligence. Why should there be such a concentration on this particular chromosome (1)? Zechner et al. (2) suggest that the X-chromosome has been engaged in the development of sexually selected characteristics for at least 300 million years and that natural selection has favoured the development of X-linked genes that are associated with higher cognitive abilities. In particular, males are more likely than females to be influenced by haplotypes that are associated with exceptionally high abilities. For an equivalent reason, they are also more likely to show deficits in mental abilities than females because of the impact of deleterious mutations carried in haploid state. The hypothesis offers an explanation for the higher male variance in many aspects of cognitive performance (3)."

So, in sum, extremely intelligent fathers = intelligent daughters (depending on intelligence of mother) whereas intelligent mothers = intelligent sons (regardless of father) and intelligent daughters (depending on intelligence of mother)?

This is consistent with me being significantly more intelligent than my father.

I think so.

(And hey, since it works for me too, I'm going to stick with it! )

It works for me, too. I've clearly passed my brain down to my daughter, which I got from my mom, which she got from her father.

Yes; potentially. Extremely intelligent fathers and/or extremely intelligent mothers = (extremely) intelligent daughters.

This has recently been de-bunked, using an elegant twin-study method: http://link.springer.com/article/10.1007%2Fs10519-012-9552-z?LI=true

That is, boys do seem to have greater variance in cognitive traits, but the X-chromosome hypothesis of why that would be so appears to be false.

Yes, x-linked traits with high heritability show up in particularly distinctive patterns in family pedigrees... and while in some mental health disorders, this pattern HAS emerged (notably, in schizo-affective disorder and in some work in personality disorders, though N's tend to be small); it's not ever been shown convincingly in an empirical population study of human intelligence that I'm aware of.

Even a putative x-linkage in some known and fairly well-defined psychosis-producing and highly heritable mental illnesses has been VERY hard to pin down.

Ask families thus affected and they definitely all know it is true... but there are a lot of other genes involved in the population-wide phenomenon, apparently, because only SOME of the families have the x-linked variety.

Personally, I suspect that this is because the empirical endpoint (a complex behavioral construct) is simply a common endpoint for a wide variety of independent underlying causative mechanisms.

Asthma has also been discovered to be like this; it describes symptoms, if you will, not a disorder with a universal mechanism.

I don't know of too many neurological phenomena that this is untrue of, in fact. MOST complex behaviors have several independent underlying causes. No reason to think that inherited intelligence would be any different.

Just wondering if there is as correlation beyond level of giftedness concerning area of strength? Obviously, kids with mathematicians for parents will be exposed to more math. But do math parents always produce gifted in math kids? Or is it just as common for a musical or verbal, or whatever domain, to spring from such parents? Do kids with LoG in all domains come from same type of parents? Or is it just as likely that they come from parent/s with only a single strength?

Our most 2E child has exactly 15 points difference in FSIQ from her sister, more like 20 in VIQ (same tester and test used), more like 10 points in NV... The youngest has not been tested and is very different from both her sisters, but also similar in many ways. At a guess she will be within 5-10 points of miss HG+.

This article from 1996 says that intelligence is x-linked. I followed the advice in the last sentence.

http://www.independent.co.uk/news/brainy-sons-owe-intelligence-to-their-mothers-1339099.html
Brainy sons owe intelligence to their mothers
GLENDA COOPER

Intelligent men owe their brains to their mothers, according to research published today in The Lancet.

Growing evidence shows that several genes which determine intelligence appear to be located on the X chromosome, the one men inherit from their mothers .Any mutation on the X chromosome has more effect on a man than a woman because a woman inherits X chromosomes from both her parents, which tends to dilute the gene's impact.

But a man only has one X chromosome inherited from his mother, which is paired with the much smaller Y chromosomes from his father. Therefore, an intelligence-enhancing X gene has more of a chance of becoming the predominate gene, determining the man's basic intelligence, looks and character. It also works the other way; if the predominate gene is not as strong as it should be, the man is more likely to suffer mental retardation.

Professor Gillian Turner, the author of the study, said: "If the gene is the one that increases intelligence then its full effect will be seen in men, while in women the benefit is less pronounced. This explains why some men are extraordinarily intelligent." She concludes that if a man wants smart sons his best bet is to marry a smart woman.

I have three that could be identified as "gifted" depending on your definition. My older two have been identified by the school system based on COGAT (they both had the same composite percentile but a very different subscore profile). My youngest has not yet been tested by the schools but we have independent WISC scores for all three. Their FSIQs are slightly more than a 10 point spread, but mine with the lower score has motor/visual integration issues, which likely impacted her testing (e.g. block design).

That being said, the one with the lowest WISC score has a significantly higher VCI than both her sisters. And for what it's worth, I even questioned whether the one with the highest WISC was gifted at all. In other words, not all gifted children, even siblings, are gifted in the same way.

Certainly not. My father is very gifted in math. I am definitely not. None of his children are gifted in math, actually. I don't think any of us even took calculus.

We actually have extreme, prodigy-level math talent in the extended family (more than one person). I think my father is still hoping those genes will pop up again. (We'll see.)

My dad is pretty smart (he doesn't have an IQ score but you know smart when you see it) and has an engineer degree and began in computers when they took up entire floors of buildings.

My mom isn't unintelligent but she was no student in her day. She has very good intuition and organizational skills and problem solving. If I had to guess above average in intelligence but horrible study skills.

My parents have two HG/PG sons...one mathy (CFO of a company) and one has a career in words.

I never had a IQ test like my brothers and always felt "less smart" than them...but other than procrastination school was pretty easy for me. I tend to think my thing is words and arts and creativity but I liked math. I just didn't live for math. I could have kept going and held my own I just didn't need it and didn't see the point. I had the ability just not the love.

I have a sister who took on the role of the ditzy one of the family but it is all an act that she turns on and off as the situation changes. If I had to guess probably above average but not gifted and it was probably a defensive mechanism living as the baby in a family with a bunch of older HG/PG kids and dad. She is also very creative/artistic with a career that uses that plus business (so math isn't scarey to her).

I don't know the answer to if your parent is Mathy will the children be mathy. I know that all of us (well maybe not my sister) could have gone as far as we wanted to in math but only one had the love to follow that path and we all had different strengths.

My DD chooses to use her brain on different things than I would, and vice-versa, because we have some significant differences in personality. But I tell her that I have the user's manual to her brain. How she learns, how she processes information, and how she expresses information, are mostly mysterious to my DW, and very familiar to me. For instance, when DD was 3 and telling an anecdote, she'd reach for stuffed animals or the salt/pepper shakers to reenact the incident, DW thought it was so bizarre, and I was like, "Oh yeah, I get that."