This thread about the possible link between ADD (or AD/HD for accuracy 
) The paper’s authors remark that
Does anybody know the relative concordance b/w mono- and dizygotic twins? How about siblings generally? Anything else relevant will be appreciated.
ADD and ADHD are usually not considered heritable traits, so identical and fraternal twins, and general siblings have little importance when speaking of the heritability of the disorder in Question.
Both my parents do not have ADD I, however, do. The abstract of the Linky in your quote says:
To me, the antecedents of ADD lay in the nurture area vs the biological. I would be grossly innaccurate if I were to say there are NO biologic origins of the disorder, however, I do believe the biologic antecdents are nominal.
I guess I don’t understand. If the concordance is higher for identical twins than fraternal twins, or siblings in general, why would that not imply a biological component?
Are you talking about the heritability of ADD/ADHD in fraternal and identical twins, and general sibs? Or are you asking about the heritability of the disorder in general?
My answer to you was that the heritability of the disorder in question is low. I believe the model of nature v nurture applies here and that nurture takes precedent over biology (meaning the heritability) in this case. The link you provide is to a study in Pediatrics. It speaks of T.V. and it’s link to ADD/ADHD.
Tho I did not read the entire study…I do not see a correlation to this discussion…
I didn’t know there was a difference. I thought the use of twin studies, i.e. identical vs. non-identical (and I add sibs because I don’t see how a couple year difference should be that important is creating a disorder) was one of the ways that researchers established the heritability of some observed event. In this case, the event is “has ADD/ADHD.” Evidently I was mistaken (?).
To which discussion? This is a new thread I started because the previous one was about how to keep kids away from television. In the paper, the authors say that there is a concordance between identical twins that is higer than it is between fraternal twins, but that environment isn’t taken into effect in the twin studies. Which makes me wonder why we have twin studies to begin with, if not to wash out the environmental factors. Two kids born on exactly the same day to the same family—wouldn’t that eliminate myriad environmental differences?
js_africanus - you do know I was the author of that last thread, right? The thread you linked to…
Because ADD and ADHAD are teetering on the psychological and biological model of the disorder, it is extremely difficult to assign a trait to two gene pools that will create the disorder from heredity. Children of a specific gene pool are all different. Each child, (even identical twins), has different perceptions of the world. ADD and ADHD are (in my opinion) correlated more heavily to the environment than to biology. This is my own view from reseach I have done, read, and participated in.
Be that as it may, the amount of time between siblings has a huge effect on their individual perceptions. Psychologists generally agree that if you have two children born more than 7 years appart that they are psychologically raised in the same way as an only child would be.
Not necessarily. They may be in the same environment, but they certainly have two very different perceptions of said environment. On the subject of twins: You may have identical twins in a family. They may be raised exactly that same, but one may want to be a gear head and fix cars for a living whilst the other wants to be a partner in a huge law firm. Environment plays a huge role in ones upbringing.
Do you have any good references that summarize the arguments well? And do you know what the correlation (or whatever it is) is between fraternal twins?