How birth order plays a factor in your relationships
(Do you concur?)

If you’re an oldest child It’s no coincidence that most U.S. Presidents were first-borns: This is the sign of natural leaders. You’re a take-charge person, so not the type to drive friends and romantic partners crazy asking questions like, “I dunno where we should eat—where do you want to go?” Instead, you’ll make sure you have reservations—and land a prime table, too. And anyone lucky enough to pair up with you won’t spend weeknights wondering whether he or she has Saturday night plans, because “oldest kids are planners,” says Dr. Leman. You’re also old-fashioned—in a good way. You always come through on anniversaries and Valentine’s Day.
Your love challenge: Being more spontaneous. First-borns aren’t the seize-the-day sort (you’re not one to text your sweetie to suggest meeting at this fun café you just walked past). Likewise, “you hate surprises,” Dr. Leman warns. Pity the fool who springs meeting the parents on you or when you thought it was just the two of you are going out!
Best match: Youngest child. “It’s a case of opposites attracting,” says Dr. Leman. “You help the last-born be more organized, and the last-born helps you lighten up.”

If you’re a middle child Contrary to their rep as insecure messes (think: Jan Brady), middle kids actually make stable and loyal partners. “One thing you’re not is spoiled,” Dr. Leman says. You probably grew up feeling you got less attention than your sibs, and that drives you to work for every perk—including a happy relationship. Also in the plus category: You’re “a compromiser and negotiator,” Dr. Leman notes, so you’ll give your partner plenty of say in everything from how quickly your relationship progresses to where you go on vacation together. And your romance should be free of daily petty squabbles (middles hate conflict); instead, you try to put others at ease.
Your love challenge: Opening up. Have you ever been told you’re hard to read? “Middle children can be very secretive,” says Dr. Leman. “They got hammered by the first-born and swindled by the baby, so they keep their cards close to their chest.” You’re also not the best communicator when you’re upset. But if you learn to speak up instead of holding your anger in, you’ll have a more harmonious relationship.
Best match: Youngest child. “Middles aren’t as threatened by last-borns as they are by exacting first-borns,” so the odds are good for open communication, says Dr. Leman.

If you’re a youngest child You’re all about fun. The most outgoing kids in the birth order, youngest children live to have a good time (it may be because your parents were more laid-back by the time you came along). On a typical first date you’ll have your date laughing so hard beer shoots out his or her nose. In fact, “most famous comedians are youngest children,” says Dr. Leman. A partial list: Jon Stewart, Jim Carrey, Ellen DeGeneres, Steve Martin, Eddie Murphy. And forget ho-hum plans, like dinner and a movie: You love to do the unexpected, often on the spur of the moment. You’re the type to take someone to a party, only to whisper two minutes later, “Let’s get out of here,” and then convince your date to take a road-trip to Atlantic City or Vegas for the weekend.
Your love challenge: “Babies are the least financially dependable,” warns Dr. Leman (it comes from being, well, babied). So your date may be stuck picking up the tab when your credit card is maxed out. Also, some youngest children — not you, of course! — use that last-born charm and charisma to be a bit, ahem, manipulative, says Dr. Leman. That breed of baby will leave sneak off to hit golf balls with pals, leaving his or her date to fill in at a volunteer gig.
Best match: Oldest child (they serve as a good counterbalance in a parent-child sort of way) or middle child (they value friendships, so they totally understand why you love being the life of the party).

If you’re an only child You’re a rock-solid citizen—and sweetie. “Only children are super-reliable,” Dr. Leman says. “They’re like oldest children to the extreme.” Growing up with only adults made you into a little grown-up early on—serious and dependable. You’re the rare person who will stay up half the night helping a friend or partner prep for a licensing exam or a big work presentation. You’re the type to move your partner’s car so he or she doesn’t get a ticket. Punctual and true to your word, onlies like you never leave a loved one waiting for a call or email. And you’re articulate, too, so your date can expect great conversations that really make a person think.
Your love challenge: Admit it: You’re a bit of a perfectionist. Maybe you send back steaks that aren’t cooked just so or point out a teeny-tiny stain on your date’s sweater. Also, you’re so cautious and pragmatic, you can be very slow to act (read: Someone else has to make the first move).
Best match: Youngest kid, because you balance each other out. The baby of the family adds the spontaneity and romance, while you make sure you two aren’t dining by candlelight because the electric bill never got paid!