Family. It is thought that temperament might be an inherited trait. As your child develops, you will see aspects of yourself, the baby's father, and even of your siblings or siblings of dad. Expect to be entertained.....And perhaps frustrated. You will see specific desires and dislikes early on. Simply observe, pay attention, and enjoy the learning process. Lol we do reproduce ourselves!
Attitude! Infants are born with much of their personality, or temperament. As they develop, you will see aspects of their personality show up more and more. These can include things like how well they adjust to new people and routines, how regular they are in sleep and other functions, how easy going or "high strung" they are, etc. It's important to try to understand your baby as an individual!