And your claim “ If an individual with an IQ of 100 has a child with an individual with an IQ of 80, the child will statistically have an IQ of 90, creating a downward trend”
That is NOT how IQ works.
Because intelligence is heavily influenced by environmental factors and complex genetic combinations, children of parents with extreme traits (either exceptionally high or exceptionally low IQs) statistically tend to move back toward the population average (100), rather than splitting the difference precisely or continuing a downward trend.
Unlike simple physical traits in animals (like coat color), human intelligence is a highly complex polygenic trait influenced by thousands of genetic variants, each having a minuscule effect.
Also note that throughout the 20th and 21st centuries, average IQ scores rose worldwide by roughly 3 points per decade due to improvements in public health, better nutrition, and widespread formal education—proving that population intelligence is not a fixed, declining genetic pool.
It is just not as simple as you put it. Society and Culture matters as well as nutrition, rule of law, and genetics
no it’s not precise, the combining of genes, but it gives you a good mathematical representation to predict this or that with some accuracy. And then you have to factor in the studies that find that an offsprings intelligence are calculated at approximately 60% from the maternal dna. Which is a good reason for men to pick intelligent women as mates.
But certainly, you don’t play with fire and make horrible breeding choices.
Now as for nurture, good luck. Throw trillions into education, and give ,” opportunities,” and not much is going to happen. initially there might be an increase of a few points, but over time there is a regression to the mean.When it comes to brains, you either have them or you don’t. It’s hardware. It’s a product of the protein-coding wrapped into the DNA
Also note that throughout the 20th and 21st centuries, average IQ scores rose worldwide by roughly 3 points per decade due to improvements in public health, better nutrition, and widespread formal education—proving that population intelligence is not a fixed, declining genetic pool.
........
The gain was preponderantly at the left tail of the curve.
it makes no sense to say that intelligence is not inherited. If that were the case, every animal and human on the planet’s intelligence would be as simple as the simplest ameba
Regression toward the mean. Yes.
So, please do enlighten us. What would be the expected I.Q. of the offspring in this instance (one parent with an I.Q. of 80, the other with an I.Q. of 100)?
Please give us your estimate!
My guess? The offspring would have an I.Q. of 90.
Without factoring in environmental influences, etc. - which we can't know in this hypothetical.
Regards,