My inlaws have once again confronted me with a topic that I disagree with. Help me with the necessary info I need to debate this one:
Does an person inherit their intelligence from the female, or both the male and female? My inlaws insist that it has been proven and documented that the female alone supplies the genes for intelligence. They cannot supply me with a source, except that their son is a doctor and he told them so. I think that this is mother-in-law sorcery that my father-in-law falls prey to. My wife remains neutral. My doctor brother-in-law lives in Europe so I can’t easily ask him. Don’t we inherit from each gender, influence depending on which genes in each couple are strongest,or something like that?
To your family, I say:
Phhhtthhbbbbt!
My father was a certified genius (160+ IQ). My mom’s IQ might equal room temperature on a warm summer day. My latest test showed 135.
You can inherit brain power from either, both, or neither. Maybe it was your grandparents’ genes that combined just right.
There’s also the question of whether intelligence is inherited. Theoretical capacity might be, but environment plays a role, too.
“East is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does.” – Marx
Read “Sundials” in the new issue of Aboriginal Science Fiction. www.sff.net/people/rothman
It not even agreed upon that intellegence is an inherited trait. Thus, your mother-in-law’s claims are probably self-serving bullshit. That said, I seem to get my intellect from my dad’s side of the family (a recent family reunion seems to have confirmed this, as far as my mom, dad, brother & sister are concerned. Who am I to argue?)
“I had a feeling that in Hell there would be mushrooms.” -The Secret of Monkey Island
It is agreed by pretty much all psychologists that intelligence is an inherited trait. The twin/adoption studies present evidence that is unbelievably compelling (twin correlations top 80%, siblings hover around 50%, adopted twins to different families around 65%).
Anyone not in agreement (in my opinion) is pushing a political agenda unconnected with the facts as they are presently known.
And the Nature vs Nurture debate rages on. I am not familiar with where you got those particular numbers from Cooper, but they could quite easily be right. However, it has always been extreemly difficult to seperate the effects of upbringing from the genetic raw materials a person may have. In the case you quote, the correlations are not a powerful statement without knowing the statistical significance of those experiments. In this case, wouldn’t the fact that twins who are not brought up together have less IQ in common than those who do indicate that it is a factor of upbringing rather than genetics. If IQ were genetically determined you’d expect the correlation to be equally high, regardless of how much upbringing the twins had shared. Many older twin studies were confounded by the fact that they were based on the large, extended families found nearer the beginning of the century, so when you examined twins that had been seperated near birth, actually they may have only gone down the road to live with some other member of their family as their parents already had too many children to raise, not giving a true change of environment at all.
However, before this thread heads off to Cuba and in response to the OP, I think it is all pretty much accepted that you inherit the capacity for intelligence, how intelligent you actually become is a matter of your upbringing just as much as of your genes. Since it is almost impossible to determine the difference between the “theoretical maximum” IQ your genes give you, and the actual IQ you have, surely it is equally impossible to determine who you got this “theoretical maximum” from?
Bill Ellison,
you posted ‘Does an person inherit their intelligence from the female, or both the male and female? My inlaws insist that it has been proven and documented that the female alone supplies the genes for intelligence. They cannot supply me with a source, except that their son is a doctor and he told them so… My doctor brother-in-law lives in Europe so I can’t easily ask him.’
I have severe problems with this:
-
it’s difficult to define intelligence, let alone test for it (if you’re using IQ tests, I don’t think they measure much more than ability at IQ tests!)
-
I know the human genome project is going well, but I hadn’t heard they’d isolated the ‘intelligence gene’
-
your inlaws make a ‘brave’ claim; it’s ‘proven and documented’, but they can’t supply the source. Welcome to the Straight Dope, where we like a citation (or two).
-
I’m sorry you can’t ask your brother-in-law any questions easily because he lives in Europe. Where is he? (I’m posting from Europe and we do have modern communications here, you know!).
Why doesn’t the sun come out at night when the light would be more useful? (Pratchett)
As a mother of bright children, I’d really like to believe the intellegent momma theory.
but sadly, I’m inclined to disagree. (It is only coinedental in our case)
I’m pink therefore I’m Spam
You can inherit intelligence? Wow. I was always hoping that my mother would leave me an ivory box in her will, maybe I can get some of her intelligence as well 
See those stars over there? That is the Little Dipper. I’d show you the Big Dipper, but my zipper is stuck.
In the “I read this somewhere” file:
I remember seeing (and discussing with my mother) an article that discussed a study claiming that the (or perhaps, an) “intelligence gene” may be carried on the X chromosome, and thus boys would inherit intelligence solely from the mother and girls from both parents.
Thus, there is at least one source that your inlaws could have gotten that info from. Unfortunately, I don’t recall when or where I read it, or whose/what kind of/how reliable a study it was. If the claim turns out to be genuine, I imagine it’ll show up again, both in the news and in scientific/medical publications.
Well uhm, males have an X chromosome as well. The male and female both have two sex chromosomes. Males have an X and a Y, females have an X and an X. They each give one to their child. I guess if it were carried on the X, males could only give intelligence to their daughters. I doubt this.
Also, Moonshine, you are correct. Looking at what I said I realize I stated it very badly (if not completely wrong) and I apologize. Most all psychologists believe that nature and nurture both play a significant role in intellectual development. This is easily demonstrated by feeding someone a poor diet. In another sense, it is also nurture in that cultural and family norms seem to play a significant role as well. However, a 65% correleation is extremely significant (+/- 2.5) - the fact that the correleation is not as strong as with twins raised together (80%, which is almost astounding)is really evidence of how little effect nurture can have (assuming a few baseline characteristics, such as good diet, non-abusive parents etc. - adoptions are into statistically more ‘healthy’ environments to begin with).
As for where these numbers come from - well they were in my Child Psych text book, which was in turn quoting a series of studies. Not as much detail as you might want I agree, but it should be sufficient. Anyone who wants to know more would be advised to go to their local Universities library and check the developmental psychology abstracts.
Actually, the 80% figure is seriously skewed. Most of the time, “separated at birth” means that the kids get different custodial parents in a divorce, or that one kid is sent to live with grandma. The upbringing is usually not very different, even if the children don’t see each other on a regular basis, because you’re still dealing with the same family and society. Therefore, similarities are to be expected. After all, it’s not like one kid is being raised in the Midwest while the other gets shipped off to Uzbekistan.
“I had a feeling that in Hell there would be mushrooms.” -The Secret of Monkey Island
I will be much more interested in reading explanations for the nature of inheritance of intelligence, and the measure of it, and a thousand other quasi scientific things of that nature when I find a definition of intelligence which everyone in the argument will accept
The greatest failing of most of the “evidence” one can find on what causes, or affects the development of intelligence is a nearly universal failure to be able to define it. Social and species specific measurement is touted to be accurate in three digits. What it is that is measured is a bit more elusive. Psychology is still much an art, and only a little science.
<P ALIGN=“CENTER”>Tris</P>
Isn’t it interesting that the same people who laugh at science fiction listen to weather forecasts and economists?
–Kelvin Throop, III
Trisk, I agree, the definition of what intelligence really is is pretty elusive. When I studied psychology (a few years longer ago than I care to admit) the working definition we used was that intelligence was what an IQ test measured. This works just fine for most discussions, as its not intelligence itself that is being discussed, but the differences between people, and between people and animals or computers. An analogy would be seeking the definition of water in a study comparing rainfall in the Amazon with the Sahara. Admittedly this definition doesn’t shed any light on the nature of intelligence at all, but it works fine in areas like the Nature vs. Nurture discussion, just as long as we can all agree on the one IQ test of course…
Hi Bill,
Just as it is with a lot of very easy questions, it is easier to ask than answer.
-
I’d agree completely or offer to agree to disagree with the in-laws. Unless they are a one topic couple - move on to something else. I’m sure you’ve done this!
-
Somehow a lot/most of us are brought up with idea that DOCTORS are something special, and in many ways they are. They are not perfect, they have a very incomplete education, lop sided, not very liberal, whatever… And often know very little beyond their own specialty. (SDMB MAJORMD is rare, extraordinary, unusual, special, and excluded from anything I say here.)
So asking a Doc to explain genetic concepts could very well be like asking your dog. IF you are talking about inherited genetic diseases with a OB-GYN 'cause you pregnant - he should know those things within his specialty.
For much more than that, he reads the papers, when he has time, just like the rest of us.
- I know I heard/read that same business about IQ from the mother in the press or on TV and (obviously) just ran it out the other ear. I already know it can’t be true.
Even the IQ tests (whatever they do test) give information on many brain function or ability areas. Hand to eye, motor skills, memory, reasoning, associations - I don’t remember them all. You don’t really get a number, you get a group of numbers. And they are averaged into one number - and that’s were you get meaninglessness. It’s meaningless unless you know what the underlying numbers are and know how to apply them and what to apply them to… We should do a “What does IQ mean?” thread.
It can’t be true because very little of what makes us human is under very simple genetic control. Most of what we are goes under a polygenetic “package program” (my words)that is, several genes control one thing. What we know about intelligence is that it is complicated and it has got to be a polygenetic trait or several polygenetic traits working together.
Now I’m hearing “Boxed _______” or “a ____box” implying more than or stronger bond than even polygenetic.
BTW: I think “they” are up to 1 billion human - what - genomes? now.
Maybe we should start the other thread - although I really am not interested in a discussion about what intelligence is. Most people can tell when someone is above average intelligence - at least, most people are in agreement with each other as to who is and who is not above average - its not any one thing but an entire set of characteristics that we all exhibit to one degree or another.
The IQ test is relevant to the degree that it conforms with people’s opinions. If everyone in class thinks that John is the smartest in class, and John has the highest IQ, the IQ test has been validated. If he has the lowest IQ, the IQ test is probably not very meaningful (unless it is consistently backwards!). A good test then is one that is consistent with vague opinions we have about one another’s intelligence.
Oh, and the 80% is for twins raised together. Siblings raised together only are about 50%.
Cooper,
I want to disagree with your last post. (Please don’t feel that I’m following you around the board - you just make interesting posts on subjects I like!).
You said ‘… I really am not interested in a discussion about what intelligence is. Most people can tell when someone is above average intelligence - at least, most people are in agreement with each other as to who is and who is not above average - it’s not any one thing but an entire set of characteristics that we all exhibit to one degree or another.
The IQ test is relevant to the degree that it conforms with people’s opinions. If everyone in class thinks that John is the smartest in class, and John has the highest IQ, the IQ test has been validated. If he has the lowest IQ, the IQ test is probably not very meaningful (unless it is consistently backwards!). A good test then is one that is consistent with vague opinions we have about one another’s intelligence.’
Sorry, but this is terrifyingly vague compared to say height or disease or eye colour inheritance. You can measure height exactly, detect the presence of colour blindness etc.
You don’t define intelligence, and you say MOST people can tell if someone is above average OR NOT - this is not scientific evidence!
IQ tests are apparently valid only if they agree with people’s preconceptions. What sort of precision is that?!
You might as well try to measure charisma. (Mind you, Salma Hayek’s got plenty of that - or is that sex appeal / beauty / charm? Well, you see my point).
Why doesn’t the sun come out at night when the light would be more useful? (Pratchett)
I’m going to relay what my coworkers college physcology ( I Think) professor told her about IQ and kids. ( This was after our boss declared one of her sons a genius ( the other is a dope) )
The Coworker went to the professor with this situation and he said,
“Kids are rarely any more than a couple points higher than their parents in IQ tests. It’s rare that you’d have a genius with two average parents, very rare.”
So, if you believe in hearsay, this works for me.
As I like to say, " I never let my schooling interfere with my education." Mark Twain.
Cooper,
Have you ever wanted to take bets on something when you know you shouldn’t?
That’s how I used to feel when we got to IQ testing for gifted programs in public schools. The number of times we guessed correctly which kids needed testing for gifted programs was always surprising. If I’d gone ahead and taken bets I’d quote the numbers for you now, darn.
Saying, thinking, wishing and even “knowing” this or that child was gifted did not make a bit of difference. It just doesn’t work that way.
Kids who dress well, have manners, are obedient, are clean (you know the drill) are often given better grades and so on, that’s true. But changing IQ scores? Not unless the school/test giver is doing something strange.
Because the IQ score is an average of several measurements you (the teacher or the average person) can easily miss children with spiked (extra high) scores in one or two area. The same happens when the child has a few spiked scores and a few low scores. These lopsided children are often told they are dumb/slow/disadvantaged/whatever by nearly everyone who knows them.
Some these variations can also show up in adults - doesn’t seem very swift but you find out later they did well at MIT.