Oh, for the women there's a .25 prob that a is used, and a .25 prob that b is used, and a .5 prob that c is used. Dad's X has the best chance, and his X may have made him a better partner than his peers. Also, a .25 prob for the X that made Mom a better partner. So, a .75 prob overall of getting a great X and a .25 prob of getting an unknown X.

For the dude there's a .5 prob of getting a great X and a .5 prob of getting an unknown X.