siblings close in IQ

[TracyP]

Quote:

Originally Posted by Karin

fwiw, it's far more likely that your dc are closer in intelligence than you can tell by what they are showing. Typically the birth siblings of a gifted dc score within a fairly close range on IQ tests even if their achievements and milestones are quite different. My eldest was the one who knew the most at a very young age and the sheer number of them combined with what they were demonstrated that she was gifted (plus other traits, and giftedness runs in the family). However, all of my dc have turned out to be gifted, even my ds who was behind in everything at 13 months. In regard to your 5 yo, her lack of motivation is a big key. Again, it's something you are born with that is potential, not necessarily something you demonstrate.

 

Can you elaborate on what I bolded? Do you have sources or is this just an observation you have made? I am curious because I'm sure ds(5) is gifted, dd(7) is "just bright" but sometimes I suspect she is not reaching her potential because she shuts down when things get hard, and sometimes I wonder if ds(3) has ld's because of developmental delays he has had. It is interesting to think they could have similar IQ's just different personalities.

[Laura Corin]

The only source I have found for this belief is some research done by the Gifted Development Center in Colorado. I seem to remember that they based it not on all siblings in a family, but on those whom the parents chose to test, so there might have been other children left out of the testing who would have skewed the results. The reference I have given to their website doesn't mention the self-selection issue though, so it's possible they have done further research.

 

I'd be happy to hear of other research on this.

 

ETA: Calvin was tested at the GDC. Hobbes has not been tested. I suspect that they are similar in intelligence, but they are such different personalities and their intelligence is displayed in such a different way that I don't know if they would test similarly.

 

Laura

Edited February 10, 2011 by Laura Corin

[brownie]

I've read the same thing...though I don't recall where. Specifically it said that statistically a variance of more than 10 IQ points between siblings is unlikely. My oldest 2 are very different but sure enough when tested, the preference I saw for analytical vs. verbal amounted to about 2 IQ points difference between them, and if you plotted their subtest scores it was eerily similar...their strengths and weaknesses were all identical and their overall IQ exactly the same.

 

I can tell you they are very different in the classroom!

Brownie

[wapiti]

I read the same thing, and it seems correct to me, based on the families that I know (particularly adults).

 

About a year ago, we had my three older kids tested. They have different personalities and different strengths and weaknesses, or so it seemed. Their test results, which were "complicated" according to the psych (they're 2E-ish, so not plain vanilla gifted), were shockingly similar. As they get older and their issues shake out a bit, I'm looking forward to testing them again, maybe next year.

[Crimson Wife]

Back when I studied psychology in college, one of my textbooks said that siblings typically have IQ scores within 5 pts. of each other. I know that my middle brother's overall IQ score is the exact same as mine, but skewed differently (mine is higher on verbal, his on non-verbal). The same thing happened when he took the SAT (same overall but somewhat higher on math & somewhat lower on verbal). My youngest brother was never formally tested but his SAT score was within 10 pts. of mine & our other brother's so I would assume that his IQ is also similar.

[Gratia271]

I have read this in research and was also apprised of this by the PhD examiner when our children were tested at the GT school. How this "appears" varies widely among my children, but there are not wide differences in IQ.

[Gratia271]

Quote:

Originally Posted by Karin

fwiw, it's far more likely that your dc are closer in intelligence than you can tell by what they are showing. Typically the birth siblings of a gifted dc score within a fairly close range on IQ tests even if their achievements and milestones are quite different. My eldest was the one who knew the most at a very young age and the sheer number of them combined with what they were demonstrated that she was gifted (plus other traits, and giftedness runs in the family). However, all of my dc have turned out to be gifted, even my ds who was behind in everything at 13 months. In regard to your 5 yo, her lack of motivation is a big key. Again, it's something you are born with that is potential, not necessarily something you demonstrate.

 

Can you elaborate on what I bolded? Do you have sources or is this just an observation you have made? I am curious because I'm sure ds(5) is gifted, dd(7) is "just bright" but sometimes I suspect she is not reaching her potential because she shuts down when things get hard, and sometimes I wonder if ds(3) has ld's because of developmental delays he has had. It is interesting to think they could have similar IQ's just different personalities.

 

The topic about achievements and milestones is what I was trying to reference in my post about early reading and giftedness. Some of the most profoundly gifted individuals are late bloomers. Some are never academic performers and can in fact "appear" rather dull. These children often will not thrive in a traditional academic atmosphere.

[zaichiki]

My two oldest were tested with similar overall IQ scores, though their strengths and weaknesses are wholly different. One has the subtest peaks and valleys that suggest 2E. The other has dyslexia. My third hasn't been tested, but is showing a similar pattern with his achievement, skill acquisition, and thought processes (leads me to believe he'd be ID'd as gifted with testing). Who knows about the baby?

 

I was tested as a child and, although not given the number, ID'd as gifted. Dh was IQ-tested as a teen and scored high, but just lower than whatever number was need to be ID'd as gifted. He was an extremely recent non-English-speaking immigrant at the time. I'd wager he'd have blown the top off whatever test that was if he would have taken it in his fluent/native language.

[regentrude]

To add anecdotal evidence: both my kids are tested gifted with an IQ within 2 points of each other. Aside from that, they are two entirely different personalities: one is an extroverted ambitious perfectionist overachiever, the other one an introverted happy-go-lucky minimalist.

[Mandamom]

I have a daughter (8) and her oldest brother (my dss 18) who are more than 10 points apart on a full-scale IQ and more than 20 points away on the verbal section. DD8 is very low in processing score which affects the full scale. She is academically inclined and motivated

 

My 10 year old daughter is closer in score to my dss18.

 

The middle brother (dss 15 -- my daughters' other brother) is closer to my dd8 in IQ. (He is probably ADHD and has just about zero interest in school).

 

I'm beginning to think that my ds5 is closer to the ds8 and dss15 although I don't know for sure yet. Depending on how long it takes to remediate his speech delays we'll determine whether or not to do further testing.

 

 

As an aside, DD10 and DSS15 are most similar in personality and interests; while Dd8 and DSS18 are most similar in personality and interest. So far DS5 is probably a mixture of the two different groups.

 

Anyway, just thought I'd share.

[2smartones]

I recently met Dr. Silverman when she was doing a seminar tour. In her seminar, she clarified why she thought siblings were close in IQ's. She said:

 

Out of 184 sets of siblings she personally tested, 100% were within 10 points of each other's IQ UNLESS there was a clear reason for them not to be (like adoption or half-blooded sibling, a hidden learning disability, frequent ear infections and/or hearing loss, vision tracking issues, or a significant age difference at the times of testing). She believes the most accurate time to test a child is between the ages of 5 and 9. If one child is tested at 8 and the other is tested at 10, the 8 year old is likely to have a significantly higher score, because until the past couple of years, there have not been extended norms on tests. A ten year old could easily hit the ceiling on IQ tests so that their actual range wasn't measurable. It would appear he had a lower score than he actually did, because age is a factor in score calculation.

 

Of everyone she's tested (not just siblings), 95% of those who scored at least 120 had a huge spike in only one area. That raised their total score from average to gifted, because they're really good in one area, but average in others. That explains why children may be equally gifted (or not), but seem completely different in the home environment. They may have different strengths, and sometimes those strengths are easier to see than others.

 

I think personality plays a huge role in how parents view their children. For example, my oldest is very driven and methodical. He's VERY asynchonous in subject matter (he was reading at an adult level when he was 4... I never had to teach him to read, and right from Kindergarten, I could hand him an assignment and walk away. That's just his personality.). However, my younger son is the wacky, funny, creative type. Sure, he's smart, but he's not driven. He's the one who at 18 mos old would come right out and TELL you he didn't want to go to the potty, because it was so much easier to go in his diaper (he was completely independent at 17 months, but only on his terms). He wants things done on his schedule and in his way. I know without a doubt he could graduate several years early, but I don't think he will. He just doesn't care. He can out-smart his brother in a puzzle sort of test (games, etc.), but he's not keeping up with the level of output I've seen the older one doing. A teacher in a PS setting who didn't know they were brothers, didn't know their personalities, etc., would assume the older one was gifted but the younger one was just a class clown. In fact, they're both equally gifted.

Edited February 11, 2011 by 2smartones

[TracyP]

The only source I have found for this belief is some research done by the Gifted Development Center in Colorado. I seem to remember that they based it not on all siblings in a family, but on those whom the parents chose to test, so there might have been other children left out of the testing who would have skewed the results. The reference I have given to their website doesn't mention the self-selection issue though, so it's possible they have done further research.

 

I'd be happy to hear of other research on this.

 

ETA: Calvin was tested at the GDC. Hobbes has not been tested. I suspect that they are similar in intelligence, but they are such different personalities and their intelligence is displayed in such a different way that I don't know if they would test similarly.

 

Laura

 

Thanks for the link. This site had a LOT of very helpful information.

 

Thank you all! I have to say this has been eye-opening. I have never considered that my dd could be gifted because she is not academically driven. She has confused me though because she has more of the gifted "quirks." She has asked deep questions since she could talk, I had people outside the family wonder aloud if she was OCD(this has gotten so much better), she does not relate well to her age peers; this just really changes the way I view her. I doubt I will ever test my oldest two. It just wouldn't change anything. But it does make me wonder about testing my 3 yo. Hmmm, I think I'll save that for another thread. Thanks again.

[Jenny in Florida]

I think personality plays a huge role in how parents view their children. For example, my oldest is very driven and methodical. He's VERY asynchonous in subject matter (he was reading at an adult level when he was 4... I never had to teach him to read, and right from Kindergarten, I could hand him an assignment and walk away. That's just his personality.). However, my younger son is the wacky, funny, creative type. Sure, he's smart, but he's not driven. He's the one who at 18 mos old would come right out and TELL you he didn't want to go to the potty, because it was so much easier to go in his diaper (he was completely independent at 17 months, but only on his terms). He wants things done on his schedule and in his way. I know without a doubt he could graduate several years early, but I don't think he will. He just doesn't care. He can out-smart his brother in a puzzle sort of test (games, etc.), but he's not keeping up with the level of output I've seen the older one doing. A teacher in a PS setting who didn't know they were brothers, didn't know their personalities, etc., would assume the older one was gifted but the younger one was just a class clown. In fact, they're both equally gifted.

 

We've never done any formal IQ testing with our kids. We played with the idea a lot when my daughter was younger, but never actually took the plunge. (We knew from very early on that she was likely extremely bright. If we were going to pay out of pocket for testing, we wanted at least a good chance we would get meaningful results. There was no one we found locally who seemed prepared to do anything more than pretty basic testing. And we couldn't afford to travel to complete the process.)

 

So, this is going to sound really silly and meaningless, but I'll tell the story, anyway.

 

Years back, I bought a book that has some IQ tests in it. I'm sure they are old, invalid, whatever. But it was cheap, so I thought I'd give it a try.

 

We gave our daughter both formats of the test (one fill-in-the-blank, one free answer) on different days when she was about six, I think. The results were similar. I flipped to the back of the book to do the scoring and discovered that the charts for her age didn't go high enough to get a score. I extrapolated as best I could, made a note of what I had figured, and e-mailed my husband that, indeed, we'd need to look for an evaluator who could cope with highly gifted kids.

 

Now, this is the daughter who consistently worked way above grade level and ended up going away to college at 12.

 

Then there's my son, whom I adore and who makes me laugh harder than just about anyone I've ever met. While his big sister was talking at nine months, this one didn't say "mama" or "dada" discriminantly until he was two. My daughter was reading Harry Potter at age five, and my son didn't manage Frog and Toad until he was seven. She started college at 12, and there are days I wonder if this one will ever get admitted anywhere . . .

 

You get the picture.

 

But, I found that book one day and, on a lark, gave my son one of the tests. He didn't seem to pay much attention or take it very seriously, but he did it. I noted the results, flipped to the back of the book and discovered that, adjusting for age, his score was actually about two points higher than his sister's.

 

So, it's nothing official, but it does seem to align with all that research. Their personalities, interests and strengths may be different, but the basic horsepower is pretty much equivalent.

[zaichiki]

A teacher in a PS setting who didn't know they were brothers, didn't know their personalities, etc., would assume the older one was gifted but the younger one was just a class clown. In fact, they're both equally gifted.

 

Excellent point here. The IQ tests can be quite revealing!

[zaichiki]

But, I found that book one day and, on a lark, gave my son one of the tests. He didn't seem to pay much attention or take it very seriously, but he did it. I noted the results, flipped to the back of the book and discovered that, adjusting for age, his score was actually about two points higher than his sister's.

 

So, it's nothing official, but it does seem to align with all that research. Their personalities, interests and strengths may be different, but the basic horsepower is pretty much equivalent.

 

Now THIS is interesting! Of course the tests aren't valid, but it certainly makes you wonder, doesn't it. Equally silly and meaningless, but -- have you ever wondered about possible LDs in your son? I only ask this b/c we found dd has dyslexia and so hidden LDs can sometimes be on my mind.

 

There have been times when we have thought that ds must have been much brighter than his sister. There have been other times where it has been totally clear that the sister seemed so much quicker to develop certain skills and/or certain things came SO much easier to her and so we were certain *she* was much brighter. Ha! (not that it matters one iota, just normal parental observations)

 

Dd is the more socially-interested child -- very personable and friendly, valuing her friendships above anything academic. Ds is more inclined to stick his head in an encyclopedia and can be socially awkward. These traits certainly can make ds look more like the brilliant kid and dd look more typical. There are academic areas where dd seems more typical and they tend to be those areas more directly affected by the dyslexia. Dd *does* have her amazing strengths, though, like her brother.

 

I'm enjoying watching my 3rd child develop: he seems to have some traits of his older brother, some of his older sister, and some that are completely new to our family. So go figure!

 

I found it interesting that one pp wrote about kids having a huge spike in one area. I wonder if that's what we're seeing when we see traits that make one dc seem "more gifted" than another (when in truth they probably have VERY similar overall IQ scores).

[Jenny in Florida]

I found it interesting that one pp wrote about kids having a huge spike in one area. I wonder if that's what we're seeing when we see traits that make one dc seem "more gifted" than another (when in truth they probably have VERY similar overall IQ scores).

 

My son is weird. (I say that with much love, since "weirdo" is a term of endearment in our home.) In testing, he is just above average in math and science and almost off the charts in reading and vocabulary.

 

I gave him the CogAT a couple of years ago alongside the ITBS. His subtest scores ranged from the 69th percentile (quantitative) to the 99th (verbal), resulting in a composite of 94.

 

On his testing last year, he did okay on the conceptual math, pretty awfully on the computational stuff, very well on the reading comprehension and missed NO questions on the vocabulary.

 

My daughter has a similar gap between math/science and language, but it's not nearly as dramatic as her brother. The English stuff is definitely more of a strength for her, but she doesn't top the charts there. And her math scores are better than his.

 

It reminds me of how they like to travel, actually. Because my daughter is in school 800 miles away, we've been making a lot of road trips for the last three years. My daughter's preference is to just get in the car and drive as constantly as possible. Ideally, she likes to sleep in the car and just get the drive over with as quickly and painlessly as we can manage. For her, the trip is about getting where you are going.

 

My son, on the other hand, likes to listen to audiobooks, look out the windows, get off the road a lot for snacks and to run around at rest stops, read billboards, talk about the meaning of life, etc. For him, the trip is part of the experience.

 

It all evens out, more or less. I keep telling him life isn't a race. By the time they are both in the 20s, I suspect they'll be in similar places in their lives.

They just like to take different paths to get there.

Edited February 11, 2011 by Jenny in Florida
typo

[Storm Bay]

The only source I have found for this belief is some research done by the Gifted Development Center in Colorado. I seem to remember that they based it not on all siblings in a family, but on those whom the parents chose to test, so there might have been other children left out of the testing who would have skewed the results.

Laura

 

I recently met Dr. Silverman when she was doing a seminar tour. In her seminar, she clarified why she thought siblings were close in IQ's. She said:

 

Out of 184 sets of siblings she personally tested, 100% were within 10 points of each other's IQ UNLESS there was a clear reason for them not to be (like adoption or half-blooded sibling, a hidden learning disability, frequent ear infections and/or hearing loss, vision tracking issues, or a significant age difference at the times of testing).

 

I think personality plays a huge role in how parents view their children. .

 

Thanks.