Multiply and Replenish the Earth

[SoonerCoug]

Originally Posted by UtahDan

Now, if you tell me that IQ is predominantly environmental (or even that this is a large factor) and you tell me that there are biological disadvantages in utero to having had many others there before you, then my thinking would change. If either of both of those things are true, then it should also be true the the first child, on average, has the highest IQ with each subsequent sibling having a lower and lower average IQ. Do you know whether this is the case?

I don't know whether IQ is primarily genetic or environmental, but I had always learned that it was primarily genetic. Certainly there are also environmental contributors.

I don't know whether subsequent siblings have lower and lower average IQs. I'm mostly just speculating based on those reviews, which may not be entirely reliable. (Sometimes reviews summarize both strong and flimsy data from papers, and it's hard to know how solid a conclusion is without looking at the primary data.) There seems to be a lot of agreement on the family size/education/IQ correlation...but it's impossible to know why the correlation exists, if it's not because of socioeconomic or genetic factors.

[SoonerCoug]

Originally Posted by UtahDan

It just occurred to me that this religious fanatic's youngest male child has a ~65% chance of being gay (because of the fraternal birth order effect).

[ute4ever]

Originally Posted by mindfulcoug

That Duggar family photo is only two years old and already two children out of date. There were 17 then, and #19 was born today.

[SoonerCoug]

Originally Posted by ute4ever

That Duggar family photo is only two years old and already two children out of date. There were 17 then, and #19 was born today.

Yeah, I'll bet they'd stop having kids if they knew that male birth order was increasing the chances that their boys would be gay.