Just a request for clarification or correction to the following assumptions and implications.
An assumption is that the ten unrelated people at the beginning of the problem are five males and five females.
An assumption is that the resultant birthling, if any, enters society immediately the day following the mating, with equal chances of being involved in mating as those already existing in the society.
And, and an assumption is made that conception occurs automatically where the two parents are at least 10% related.
An implication is that each adult only performs the ritual of mating no more than once per day, and due to there being a possibility a gender surplus or shortage respective of the other gender, not every adult will mate on a given day.
An implication is that incestous matings can occur, though the result of that mating is no offspring.