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

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.