Claudia

Heritability is a concept based on correlation studies.
Huge heritability means a huge correlation between parents and childrens (or eventually other blood links).
But correlation says nothing about the average of a group.

High heritability says that variation within a group, all other things being equal has a genetic component. But as it says nothing about the average of each group, it is quite possible that this average is highly contrained by environmental/educational parameters.

High heritability usually means that either there is a genetic influence.
But it does not say that genetics has the major influence on the studied characteristics.

Some comments?

(Moderators, please feel free to move this thread if it is not in the correct forum)

squozebrain

Do you mean "heritability" as in, "being a Baptist is a heritable characteristic"?

Claudia

It could be.
But also "heigth is a heritable characteristics"

RGD

My first comment is that I'm not generally clear what you're getting at. Are you asking whether your concept is correct? Are you asking about something else? If could clarify, that would help. You may simply be asking a question about statistics. Otherwise....

Originally. It's now possible to do direct 'heritability' checks via genetic testing.

True. If I have 100 members of a population, the correlation of characteristics between members of that group directly related by blood will be high (decreasing, of course, as the degree of kinship decreases). The average of a given characteristic of that group (e.g. height) is obviously different than the actual height of any given member.

That would depend on the characteristic, wouldn't it? Again, let's take height. If the average height of a population of 100 members is 173 cm, then there is a 'genetic' component to it, since the average of that height is made up of 'genetically correlated' heights.

For things that are not directly heritable that way (e.g. income), there isn't a genetic component to it, though there may be a 'historical' component (being rich isn't a zero-sum game, in a fashion).

Not for a non-biological characteristic.

Again, it depends on what that characteristic is.

Average height in a population has a genetic component.

Average income in a population does not have a genetic component (except very, very indirectly).

Peez

Strictly speaking regression analysis, but the concept is essentially the same.Indeed, between the mean of the trait values of the parents and the mean of those of the offspring.Quite so, though I do not know why the average of the group would be of particular interest in this context.Actually any heritability implies that genetic variance is responsible for at least some of the variation in a trait.I do not follow you here.?I am going on the assumption that you are referring to "narrow sense" heritability, but please correct me if I am mistaken. It is quite possible for a trait to be entirely (for all practical purposes) genetically determined, and yet have 0 heritability. It is also possible for a trait with a very large heritability to be influenced to a very large extent by other factors, most notably non-additive genetic variance and genotype x environment interactions. However, heritability is very relevant to evolution because it is in a sense the proportion of natural selection that actually drives evolution.I am not sure if I understand you with regard to group averages and constraints, but you do seem to be on the right track.

Peez

Clutch

You guys don't know much about heritability. It's all explained here:

Hope that helps.

PoodleLovinPessimist

I thought at first for sure you must have been parodying the Bible. I was wrong. It's really in there! :rolling:

travc

I think you are pointing out that a common environment can induce similar traits in parents and offspring even if that trait is highly plastic (variable) in different envronments. That is true. But in qunatitative genetics (which it sounds like is the closest discipline to answering your question), the envrionment (and variability in the envrionment) is explicity accounted for.
You end up saying things like "Trait X has a heritability of Y in environment Z".

Even more importantly, you don't just look at the how similar offspring are to parents... instead you look at how much of the variation amoung a group of parents accounts for the variation seen in the offspring. (Interestingly, a trait that is so highly constrained by the envrionment that it does not vary cannot be heritable by this definition.)

Some references:
http://www.ndsu.nodak.edu/instruct/m...tgen/qgen5.htm
http://biomed.brown.edu/Courses/BIO4....genetics.HTML

Nice Squirrel

So that's what happened to the chipmunks!

Clutch

Oh, that biblical idea was cutting-edge science for millenia!

The Works of Aristotle the Famous Philosopher went through many, many printings in Victorian England. It's not by Aristotle; in fact it's a hodgepodge of sex tips and birthing advice, some gleaned from various writers of antiquity, much of it the common wisdom of the day, and no doubt a good deal just made up on the spot. (I think it was popular because it said ARISTOTLE on the spine, so it could be read in public, but was primarily about sex.)

Anyhow, check out this widely-read account of human heritability:

Three striking features: this is essentially the Genesis theory of heritability; it explicitly encourages paternity paranoia in husbands; and it must have caused unbearable guilt in mothers of disabled or disfigured children. Yuck, on all three counts.