8. Recognizing Relatives

Stanford University.

--push off into new terrain, here-- yet another bucket.

But before doing that, various bits of feedback

from office hours.

Hearing from TAs.

Getting a sense of where the grand, gaping craters

of confusion are so far.

And apparently an awful lot of them

were provided in the last two days of lectures

with behavior genetics.

Various issues that came up.

Clearly, one of the most complicated, inaccessible,

subtle, pain in the neck concepts

in the whole class, which is this heritability business.

So memorize the following two sentences,

because it all comes down to the difference between something

that is inherited and how heritable a trait is.

The fact that humans overwhelmingly

have five fingers reflects the fact that the number of fingers

is an inherited trait.

The fact that, when there are some circumstances of humans

having other than five fingers, it

is overwhelmingly due to environmental

something-or-others is an indication of the fact

that, nonetheless, variability around the number of fingers--

heritability is essentially 0%.

So get those two sorted out, and you

have those two concepts all under your belt

and very useful.

Why is it useful?

First off, why is this one useful?

Because it is important to know the distinction.

Everybody, for one thing, out there

tends to view these as telling the same thing.

And insofar as they think it says the same thing,

they think that both terms are referring to this.

Something that is genetically regulated, genetically

determined-- whatever.

Two totally different terms.