One more thing to consider is that IQ is caused partially genetically, and partially non-genetically, e.g. diseases or lack of nutrition decrease IQ. So if you e.g. examine people from a sick and starving population, of course they are likely to have below-average IQ. But that doesn’t say anything about what IQ their descendants will have if the food and health problem gets fixed.
Intelligence is a polygenic trait, i.e. a trait influenced by multiple genes. There is an observed regression to the mean, that is although smart parents are likely to have smart children, and dumb parents are likely to have dumb children, the children of either are usually closer to the average than their parents.
In other words, if you would inhabit an island exclusively by Mensa members, the children born on this island would probably almost all have above-average intelligence; but many of them would not reach the Mensa level. Or the opposite experiment… well, this one was actually done in real life… 40-50 years ago when communists ruled Cambodia, they killed almost all literate people in the country in the attempt to create an agrarian utopia (spoiler: didn’t work as advertised), but Cambodia didn’t literally become a nation of retards.
It is difficult to find exactly which genes contribute to IQ. There are more than 50 suspects, but the experiments suffer from low sample sizes, so many of them are probably false positives.
It seems that first-born children have higher IQ than their siblings. (The official story seems to be that it’s because they get more parental attention and resources. To me it seems more likely that children born later simply receive higher mutational load from older parents. But maybe it’s both.)
It was suspected that breastfeeding increases IQ. Then it turned out this correlation was caused indirectly by mother’s IQ; i.e. smart mothers are more likely to breastfeed their children, and smart mothers are likely to have smart children, which creates a correlation between smart children and breastfeeding even if breastfeeding has no real effect on IQ. Later, there was an experiment showing that actually children with some genes may benefit from breastfeeding while children with other genes may not… but the experiment is unrealiable because of small sample size. (If you start researching this topic seriously, you are going to hear “small sample size” depressingly often.) If true, this wouldn’t be completely suprising, because similar effects are known; for example people with phenylketonuria are more likely to become retarded unless they get a special diet in which case there is no impact on IQ.
tl;dr—it’s complicated; people who pretend it isn’t are either stupid or lying, don’t be one of them
One more thing to consider is that IQ is caused partially genetically, and partially non-genetically, e.g. diseases or lack of nutrition decrease IQ. So if you e.g. examine people from a sick and starving population, of course they are likely to have below-average IQ. But that doesn’t say anything about what IQ their descendants will have if the food and health problem gets fixed.
Intelligence is a polygenic trait, i.e. a trait influenced by multiple genes. There is an observed regression to the mean, that is although smart parents are likely to have smart children, and dumb parents are likely to have dumb children, the children of either are usually closer to the average than their parents.
In other words, if you would inhabit an island exclusively by Mensa members, the children born on this island would probably almost all have above-average intelligence; but many of them would not reach the Mensa level. Or the opposite experiment… well, this one was actually done in real life… 40-50 years ago when communists ruled Cambodia, they killed almost all literate people in the country in the attempt to create an agrarian utopia (spoiler: didn’t work as advertised), but Cambodia didn’t literally become a nation of retards.
It is difficult to find exactly which genes contribute to IQ. There are more than 50 suspects, but the experiments suffer from low sample sizes, so many of them are probably false positives.
It seems that first-born children have higher IQ than their siblings. (The official story seems to be that it’s because they get more parental attention and resources. To me it seems more likely that children born later simply receive higher mutational load from older parents. But maybe it’s both.)
It was suspected that breastfeeding increases IQ. Then it turned out this correlation was caused indirectly by mother’s IQ; i.e. smart mothers are more likely to breastfeed their children, and smart mothers are likely to have smart children, which creates a correlation between smart children and breastfeeding even if breastfeeding has no real effect on IQ. Later, there was an experiment showing that actually children with some genes may benefit from breastfeeding while children with other genes may not… but the experiment is unrealiable because of small sample size. (If you start researching this topic seriously, you are going to hear “small sample size” depressingly often.) If true, this wouldn’t be completely suprising, because similar effects are known; for example people with phenylketonuria are more likely to become retarded unless they get a special diet in which case there is no impact on IQ.
tl;dr—it’s complicated; people who pretend it isn’t are either stupid or lying, don’t be one of them