Babies differ in the following aspects due to their genetic make up and conditions in the womb;
- Vigor of responding.
- General activity rate.
- Sleeping rhythms.
- Irritability.
- Rate of habituation.
- cuddliness
- Sensitivity to light and or sound.
- In size and shape.
- In absolute and relative size of body organs.
- In hormonal balance.
- In blood chemistry.