There were double beds, if you set a man and a women (their attributes have to be similar or something) in a bed, the women become pregnant. While the woman is pregnant, she can’t do any work, and she eats extra. She is also extra vulnerable to goblins (the goblins are attracted to her baby and there are double, so whenever you push R, or do the defensive stance, she will run to a nearby house while other villagers will defend). Her baby will have mixed attributes between the father and mother.
I moved a post to an existing topic: Thoughts on Children and Population Growth