@Sunnyyesjams
For one reason or other, my sim children often favour their grandparents (especially in terms of the haircolour. Catherine has her grandfather´s hair, Miles on the other hand has his grandmother´s colouring, who was a IF, hence the dark red head hair with the yellowish brows and beard.)
I often have face clones, though the body shape and colouring vary. Real blending is seldom. I think, there´s a setting in nraas storyprogression for that, I really should try that.