Maternal grooming, that pups receive can influence how much they groom their own pups and influences later corticosterone responses to stress (Latham & Mason, 2004). Mouse pups are born without hair. When they begin to grow their first coat, their eyes are still closed. At such a young age, the dam must groom their coats for them. This serves a physiological and psychological purpose, because it strengthens the maternal-social bond.