Are personality traits important? - People

Family Roles
Sibling rivalry: Finding a niche
Split-parent identification is stronger among sibs raised
together and stronger in same-sex sibs
First borns dominate and care for their younger sibs, and
they also have a greater interest in preserving the status
quo.
Compared to later borns, first borns are
less open to new experiences but more responsible,
achievement-oriented, and organized than later-borns;
less agreeable, more jealous, more fearful, more
assertive, more dominant, and less sociable.