I have been thinking about the concept of selfish genes, as introduced by Dawkins, over the past few days. This led me to the following consideration. From the perspective of a selfish gene, there must be an optimal degree of relatedness, right?

This idea may appear erratic. So, please let me room to explain.


Let’s consider the parent generation. Each parent has a 50% rate of passing on their genes. Basically, yes. However, there is a way for a selfish gene to further increase its chances of being passed on, namely if both parents are related and thus already share a certain percentage of genes.

So, from the perspective of a selfish gene, there must be a trade-off between the harms of inbreeding, such as the activation of harmful recessive genes or a lack of genetic diversity, and the benefits of relatedness through an increased chance of being passed on. Formally, one can write: given a certain degree of relatedness, c is the chance of harmful mutations and recessive genes, etc., while t is the chance of passing on as many selfish genes as possible.

t >> c

How you any idea how formally caculate this?