A finite diploid population, observed at times t = 0, 1, 2, ..., is studied. An individual is said to be in age group i at time t if its age is between i and i + 1 units in that time, where i >= 1. It is assumed that the number of individuals in a particular age-sex class is the same for every t and that the probability that a male offspring was produced by a mating of a male in age group i and a female in age group j is pijm (with a corresponding probability pijf for a female offspring), regardless of when the individual is born. The probability of ultimate fixation of an allele A1 and the inbreeding effective number, for large populations, is calculated under the further assumptions that A1 is neutral and that mating is random, given the ages of the mates.