Firstborns

Firstborns are usually dominant and organized. Research shows they're more conscientious than other birth orders. Nick Lachey and Jessica Simpson are both firstborns. Nick has many younger siblings. Jessica has one younger sister. Both should want to be in the driver's seat most of the time. They would be uncomfortable with anyone giving them orders or direction, especially in a romantic relationship.

Older brothers

Older brothers of brothers are the most take-charge people. John Wayne was an older brother and he typifies this birth order. Macho, dynamic, and a leader, Wayne often played tough-man roles in his films... Older brothers of sisters make good directors and are comfortable in the company of women. The best match for an older brother is a younger sister. But you can also get along with older sisters, provided you realize that you'll both want to be in control. When two firstborns date, they usually experience rank conflict.

Older sisters

Paris Hilton is a typical older sister of brothers. She's bossy, confident, and aggressive. Jessica Simpson and Nicole Kidman are both older sisters of sisters. These girls like to be in control (as do most firstborns) but they have another characteristic that sets them apart — they get along better than other girls with older men who are authority figures. If you're an older sister of sisters, you'll probably get along famously with your male teachers. The best match for you is usually a younger brother. For the older sister of brothers, the best match is a younger brother of sisters. For the older sister of sisters, another good match is a male only child. You also get along with older brothers, provided you realize that they'll annoy you when they try to boss you around. (Photo: Nick Lachey and Jessica Simpson.)