Lets assume that this means that the probability that an arbitary male is an Adam is , and a femail is . Then the probability that an arbitary couple is an Adam and Eve is .

Now in a sample of couples the number of Adam and Eves has a binomial distribution , which is approximatly Poisson with mean , so the probability of such couples is , which has a maximum at and . So we have to repeat the calculation using the binomial distribution for these, and we find:

and:

So

RonL