Birth order is really the only “unshared environment” effect that could plausibly be attributed to rearing environment. I’ll return to birth order, but we have to keep in mind what “unshared environment” means: the thing that makes MZ twins raised together different from one another. When that is kept in mind, coupled with the fact that shared environment effects are generally nonexistent, it really does collapse any putative unshared environment rearing environment effect (“it effects me only if it doesn’t also happen to my twin”)
Small shared environment effects on things like educational attainment have to be kept in context: education is signaling. The shared environment can affect the signaling component without affecting anything “real”—evident when one looks at income.
And about the income measure you note here, if you notice, the best measures (e.g., 20 year income) produce zero shared environment. There is a Wilson effect on income that washes out when long time periods are considered.
This brings us back to birth order. Tiny birth order effects on IQ are consistent with them not being Jensen effects; they are not on the g-factor and hence are not “real”. First borns do actually test better relative to how smart they truly are. The finding of a birth order effects on personality using self-reports is surprising. Generally, birth order effects on personality only turn up when family raters are used (parents, siblings), since birth order effects *do* exist in the rearing family dynamic. I’m inclined to believe that they’re not true.
1) Are all of these studies concerning modern children? Ie children born in an age when large families are rare?
2) Is there any control for sub-culture in this study? Like, sub-cultures that routinely have larger families?
Cause, you know, those would seem to make a difference. Belonging to a sub-culture (or historical group) that has lots of children, that is used to it, that has support mechanisms for it, that has cultural understandings that support it... would seem to make a difference.
Maybe I'm missing something here. I can come back to it later. I was looking to see if I should change my mind on my target family size. But, given that the "less successful' children bringing the average down are birth order effects of younger children, wouldn't there still be an advantage to having lots of children?
Is there actually a disadvantage to the oldest child to having more children, provided you have the resources to care for all of them? There could be benefits and costs to the older kids to having more younger siblings, so it's not intuitively obvious why having more kids would be a harm to any of their prospects.
Idk, I'd rather have 2 highly successful kids and 3.moderately successful ones than just the 2 highly successful ones. I suspect the 5 siblings would also have certain social advantages over the 2, but taking those out, I would prefer the 5.
People who have larger families literally are more successful children.
Need to see relationship between number of siblings and number of offspring.
Ah, but do they have fewer successful children :)
Is this accounting for differences in intelligence and personality between the types of parents who are likely to have more vs fewer kids?
So unshared environment did have a significant impact but not shared one?
Not necessarily. Family size is shared, birth order effects are unshared.
Indians reversing birth order effects was not something I expected.
Birth order is really the only “unshared environment” effect that could plausibly be attributed to rearing environment. I’ll return to birth order, but we have to keep in mind what “unshared environment” means: the thing that makes MZ twins raised together different from one another. When that is kept in mind, coupled with the fact that shared environment effects are generally nonexistent, it really does collapse any putative unshared environment rearing environment effect (“it effects me only if it doesn’t also happen to my twin”)
Small shared environment effects on things like educational attainment have to be kept in context: education is signaling. The shared environment can affect the signaling component without affecting anything “real”—evident when one looks at income.
And about the income measure you note here, if you notice, the best measures (e.g., 20 year income) produce zero shared environment. There is a Wilson effect on income that washes out when long time periods are considered.
This brings us back to birth order. Tiny birth order effects on IQ are consistent with them not being Jensen effects; they are not on the g-factor and hence are not “real”. First borns do actually test better relative to how smart they truly are. The finding of a birth order effects on personality using self-reports is surprising. Generally, birth order effects on personality only turn up when family raters are used (parents, siblings), since birth order effects *do* exist in the rearing family dynamic. I’m inclined to believe that they’re not true.
Wondering a couple of things:
1) Are all of these studies concerning modern children? Ie children born in an age when large families are rare?
2) Is there any control for sub-culture in this study? Like, sub-cultures that routinely have larger families?
Cause, you know, those would seem to make a difference. Belonging to a sub-culture (or historical group) that has lots of children, that is used to it, that has support mechanisms for it, that has cultural understandings that support it... would seem to make a difference.
(NB Father and grandfather of large families)
what about only children?
Only children are typically comparable to firstborns in IQ/education.
Maybe I'm missing something here. I can come back to it later. I was looking to see if I should change my mind on my target family size. But, given that the "less successful' children bringing the average down are birth order effects of younger children, wouldn't there still be an advantage to having lots of children?
Is there actually a disadvantage to the oldest child to having more children, provided you have the resources to care for all of them? There could be benefits and costs to the older kids to having more younger siblings, so it's not intuitively obvious why having more kids would be a harm to any of their prospects.
Idk, I'd rather have 2 highly successful kids and 3.moderately successful ones than just the 2 highly successful ones. I suspect the 5 siblings would also have certain social advantages over the 2, but taking those out, I would prefer the 5.