[brenschluss]

I'd understand your assumption but think that it is incorrect, since the paper defines desirability not as genetic healthiness but as a mechanism for sex A to select sex B:

"The actual magnitudes of these desirability values are assumed to have no significance, and are used only to make comparisons between individuals. Here and throughout, it will also be assumed that the same desirability value is assigned to each individual by every member of the opposite sex. "

[waterhouse]

The desirability of an individual is often strongly influenced by heritable traits. In the example with my interpretation, "beauty" is a trait we assume to be desirable (for the sake of illustration I'm assuming it's the only trait considered), and how much of it an individual has is heavily influenced by the coin-flip gene. I see no contradiction here.

I might interpret the sentences you quote as "We can give each individual a beauty score from 0 to 100, and all members of the opposite sex agree on what beauty score an individual gets." And we might imagine the coin-flippers have beauty in the ranges 90-100 or 0-10 (depending on the flip result), while the others are all between 40-60 beauty.

[brenschluss]

> The desirability of an individual is often strongly influenced by heritable traits.

I don't disagree with you, but that is not what the paper states, and that is not how the paper defines desirability.

I am not saying that the paper's definition is correct for a broader understanding of biology. Rather, the paper's stance is to generate a simple model and to prove an argument within that model. I am saying that, within the definition that the model is using, the model is internally incorrect.