Dominance but not majority? Why?!

[goddessxx]

This is a discussion question. I've been searching online for a while but couldn't find a satisfactory answer.

Heredity: Dominant and Recessive

Why does dominant genes does not necesarily mean that it will affect the majority of the population?

For example, having more than 10 fingers is dominant, but most people are in the recessive category, which is just 10 fingers. If that's how the traits are, wouldn't the recessive become dominant?

Thank you for all your help

[bearhug]

Recessive is always recessive. Having 10 fingers is the wild type. If everyone is homozygous recessive for this trait than it is impossible for there to be a dominant allele, unless there's a mutation.

[MrMistery]

Well, i am not sure about this example. What you are saying is that a man with polidactilia will always have children with more than 10 fingers? Seems strange.

About the frequence of an allele, have a look at hardy-weinberg. There is no direct relation between the dominance and it's transmition

[bearhug]

I think you misunderstood me.

[MrMistery]

I take it back. If a man has more than ten fingers he may be FF or Ff. So some of his children will have more than 10 fingers. Right?

[M.Shanti Priya]

Even though polydactyly is controlled by a dominant allele it is accompanied by incomplete penetrance hence not observed in majority of the population. The gene doesnot penetrate or show the phenotype associated with the genotype in all the individuals with that genotype.