Heritability

[rob171171]

Hi

 

Exploring the concept that leadership is genetically governed more so than phenotype influenced and running into the concept of heritability which, and pleased correct me if I'm wrong, asks how much genetics plays a role in the differences of makeup , both genotype & phenotype traits.

 

I'm encountering the phenomena of additive and non-additive heritability and I'm slowing drifting into the abyss trying to understand exactly what these mean.

 

Can anyone shed some light?

 

Thanks in Advance

[chadn737]

I'm not sure what you mean by "phenotype influenced" as the phenotype is in part a product of the genotype and in this case the phenotype would be "leadership". I think you have confused "phenotype" as being the same as "environment". The genotype and environment interact to produce the phenotype, which is the physical/mental/behavioral characteristic.

 

As for additive vs non-additive. Additive genetics is the idea that each gene contributes some proportion towards a trait and that variation in these genes can be added/subtracted directly to come up with the contribution of each gene. For instance, gene A contributes to 5% of the phenotype and gene B contributes to 10%, then gene A and gene B contribute 15% of the phenotypic variance.

Non-additive genetics comes into play when you have gene interactions that do not allow for such simple 5 + 10 math. This is typically due to epistasis. Say that gene A has two variants: variant 1 and variant 2. If you have variant 1, then the interaction of this variant with gene B masks any effect of gene B, but if you have variant 2, then you see the effects of gene B. So you only see the 10% phenotypic contribution of gene B if you have variant 2 of gene A, otherwise, gene B has no effect if you have variant 1. Therefore the relative contribution of each gene is not a simple gene A + gene B addition as the contribution of gene B is dependent upon gene A. Thus the genetics of this is "non-additive".

[rob171171]

Many thanks contrary one. Yes your assumption on my confusion surrounding phenotype is correct. I should have remebered this having studied, for a brief period, genetics in college many moons ago.

 

FInally!!!At last now I understand the differences. Thank you so much for taking the time to explain this. This is the 6th forum I have posted to over last 10 days and 1st reponse I have received. with a great explaination.