Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
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Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#2I'd contest the statement that "nobody’s surprised when identical twins turn out to have very similar bodies (weight, muscle mass, etc), even into adulthood." From the research I remember reading about, there does seem to be some genuine level of surprise as to how much influence genetics has over even twins separated at or near birth - and that the level of genetic determinism that twins exhibit is certainly rather controversial even amongst those that study them.
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#3Or, maybe, twins share similar thought patterns and therefore make similar lifestyle choices (how much to eat, how often to exercise, and so on) and that's why they share similar weights and muscle mass.
That said, the nature/nurture pendulum has been stuck on the "nurture" side for a while, and it's now starting swinging back to the middle where it belongs. It's got a ways to go though. I'm reading Steven Pinker's The Blank Slate now, and I highly recommend it to people who are interested in this topic.
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#4Like a-priori, I have read The Blank Slate. I'm pretty familiar with Pinker's work and the article linked here doesn't say much. As a matter of fact, it doesn't say anything helpful at all. "Why don't we apply what we know about twins to everybody?" Well, it's because the role that genetics plays in behavior isn't clear cut and well-defined.
Full disclosure: I side with nature over nurture when it comes to behavior, but I believe it's probably 60/40 or 70/30, meaning environment still plays a major role.
Sure, the cases of identical twins separated at birth is compelling. They sometimes make the same career decisions and even marry and divorce and remarry people with the same exact names.
But what about identical twins who turn out to be of different sexual orientation? What about identical twins who are almost nothing alike but raised in the same home?
Genetics definitely needs to be recognized as a significant influence on behavior and human nature, but there's a reason we don't apply identical twins studies and findings to everyone. I can't believe anyone would say, "If it applies to these people, why don't we apply it to everyone else?" It rarely ever works that way.
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#5Or, maybe, twins share similar thought patterns and therefore make similar lifestyle choices (how much to eat, how often to exercise, and so on) and that's why they share similar weights and muscle mass. That said, the nature/nurture pendulum has been stuck on the "nurture" side for a while, and it's now starting swinging back to the middle where it belongs. It's got a ways to go though. I'm reading Steven Pinker's T…
It's all nature. Nurture is what you do with it.
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#6Twins may be identical physically, but they present a challenge to the assumption that being is merely physical because they are often completely different when it comes to who they are (and what is that, really?)
I have lived with twins for 3 years (married to one of them) and you couldn't find two people more different. Physically they look the same, but as far as personality, you couldn't find two people more different.
They were both "nurtured" from the same woman, same environment, yet they are opposites. I think there is an ontological question raised. Is there a non-physical component to our existence? Something to think about.
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#7Twins may be identical physically, but they present a challenge to the assumption that being is merely physical because they are often completely different when it comes to who they are (and what is that, really?) I have lived with twins for 3 years (married to one of them) and you couldn't find two people more different. Physically they look the same, but as far as personality, you couldn't find two people more diff…
Why does a non-physical component need to be invoked? Why could there not simply be genetic mutation that affects personality but not physical stature? It seems to me that there's no reason to believe some non-physical component is at work until the physical components have been ruled out.
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#8Twins may be identical physically, but they present a challenge to the assumption that being is merely physical because they are often completely different when it comes to who they are (and what is that, really?) I have lived with twins for 3 years (married to one of them) and you couldn't find two people more different. Physically they look the same, but as far as personality, you couldn't find two people more diff…
Why does a non-physical component need to be invoked? Why could there not simply be genetic mutation that affects personality but not physical stature? It seems to me that there's no reason to believe some non-physical component is at work until the physical components have been ruled out.
(Identical) twins are genetically identical.
(edited--thanks patio11)
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#9As I'm about half done with Good Calories, Bad Calories, this post rather resonates. My mother is an identical twin and she is about as equal in stature to her sister as you can be. It's curious to me that I've always accepted that since they're twins, they must have similar body types. It is very quickly apparent to me that, because they live apart and don't eat the same things, weight and/or body type must have some genetic or metabolic component unrelated to consumption or exercise.
The disconnect between my observation and my previous thinking of obesity being related to will power or exercise habits is sort of mind blowing.
Re: Miscalibrated Minds: Why Don’t We Apply What We Know About Twins to Everybody?
#10Earlier quoted context omitted.
Why does a non-physical component need to be invoked? Why could there not simply be genetic mutation that affects personality but not physical stature? It seems to me that there's no reason to believe some non-physical component is at work until the physical components have been ruled out.
(Identical) twins are genetically identical. (edited--thanks patio11)
Monozygotic (identical) twins are. Dizygotic (fraternal) twins are not.
Actually, clarification to the clarification: fraternal twins, like any two siblings from the same parents, are merely highly unlikely to be (close to) genetically identical. For any given chromosome, you either get one of Mom's or one of Dad's. That gives you a finite number of possible chromosomal choices. Since they're essentially chosen with replacement between fertilizations (in the discrete sense of "chosen with replacement", its not like the egg says "OK, I'm done with this X chromosome mom, you can have it back now"), you could randomly end up with two siblings (and, by extension, two fraternal twins) with the same chromosome choices (i.e. pretty close to genetically identical, allowing for some minor and likely consequence-less mutation).
My naive calculation of the probability of any two siblings being genetically identical without being identical twins is 1 / (2 ^ 48), though. :)