> Whether a human is smart or dumb has nothing to do with the intelligence of their parents

You really need to clarify your statement here. Two stupid people can produce a smart kid. Two smart people can produce a dumb kid. This is true. But "nothing to do with" as plainly written like that is not accurate. Intelligence is not inherited but many factors associated with intelligence are heritable. And, of course, environment factors play a role as well. But all things being equal, two smart people are more likely* to have a smart kid than two dumb people. That's just science.

* at population levels not any individual couple

Phillip_McCavity wrote:

I think you misunderstand heritable. It does not mean "determined by genes".

Consider a simple example. People have two arms. The "thing" that leads to two arms is clearly in genes.

However, the trait of having two arms is 0% heritable.

Let's not get caught up in the definition war.

IQ is like height:

- at a population level, tall parents are more likely to have tall children than short parents
- at a population level, smart parents are more likely to have smart children than dumb parents
- the environment can impact the height of children such that it varies from their parents: for example, poor nutrition
- the environment can impact the intelligence of children such that it varies from their parents: for example, poor education

Edit: I do not mean to say that IQ and height have the same heritability rate. They do not. But height is a great example of a heritable trait. IQ behaves the same way.

lol yes it does, it has a whole lot to do with their skull
shapes.  PelvicOarfish could you tell the class about how the size and surface area of the frontal cortex matters?

Spanky wrote:

Let's not get caught up in the definition war.

IQ is like height:

- at a population level, tall parents are more likely to have tall children than short parents
- at a population level, smart parents are more likely to have smart children than dumb parents
- the environment can impact the height of children such that it varies from their parents: for example, poor nutrition
- the environment can impact the intelligence of children such that it varies from their parents: for example, poor education

Edit: I do not mean to say that IQ and height have the same heritability rate. They do not. But height is a great example of a heritable trait. IQ behaves the same way.

No, not really. We all agree on how to measure height, but brain functions are far more complex. Shakespeare would probably fail a calculus test, but neither of us can
write what he did.

Genetics do determine the development of the brain, things like how neurons grow. But how "smart" (which we largely measure by how well someone integrates with society)
someone is depends on how those neurons hook up, and that is a dynamic process that lasts for years.

Its really helpful if a kid has "smart" parents, because, as you state, they are more likely to be successful and able to provide a rich environment, growing up.

Phillip_McCavity wrote:

No, not really. We all agree on how to measure height, but brain functions are far more complex. Shakespeare would probably fail a calculus test, but neither of us can
write what he did.

Genetics do determine the development of the brain, things like how neurons grow. But how "smart" (which we largely measure by how well someone integrates with society)
someone is depends on how those neurons hook up, and that is a dynamic process that lasts for years.

Its really helpful if a kid has "smart" parents, because, as you state, they are more likely to be successful and able to provide a rich environment, growing up.

That's fine. I can agree with that.

"The ability to do well in the subjective way in which we choose to measure intelligence is a trait that is heritable in a way similar to height."

You are very correct that the way we measure intelligence is entirely subjective and excludes larges classes of intelligence.

https://www.amazon.com/gp/product/0465024335