Does birth order affect temperament?
Many parents ask this question. Parents usually do have more time and energy to attend to their first baby and lack of experience makes them more anxious to respond quickly. With the last-born, parents may be more relaxed about accepting babyish behavior. Thus parents of first and last born children may find it harder to set limits. Middle children may struggle to make a comfortable place for themselves between older and younger siblings. However a variety of research has shown that birth order has less effect than temperament.
In our Kaiser Permanente studies, we found no link between birth order and how parents rated temperament at four months. Over time, parents come to see their first, second, or third as the easy child or the challenging one, depending on temperament.