If you’re even slightly familiar with birth-order theories, the following will tell you all you need to know to figure out where 13-year-old Mackenzie Nalepa falls in her family of four children.

A couple of years ago, Mackenzie, an ice skater since she was three, had the chance to join a top juvenile figure-skating team, the Capitol Steps. But there was a catch: Practices were Saturdays at 5:30 a.m. in Arlington, Va., a good hour from her Mount Airy home.

That meant Mackenzie had to get up at 4 in the morning Saturdays to schlep to Virginia to skate.

So before they signed her up for the team, Mackenzie’s parents sat her down to explain that commitment.

They needn’t have worried. No problem, Mackenzie told them, she could do it.

She wasn’t kidding: Two years later, she has yet to miss a practice.

“She’ll be up Saturday mornings on her own, saying, ‘C’mon, I don’t want to be late,’ ” marvels her mother Mary Nalepa. “She is very driven, very organized, very independent, a bit of a perfectionist.”

Hello, firstborn child.

In the land of birth-order theory, if the last-born is the spoiled, creative clown and the middle-born the easy-going, compliant peacemaker, then the firstborn child is king.

About a century ago, Austrian psychologist Alfred Adler was the first to theorize that when a child is born in relation to his siblings — not just factors such as socioeconomic conditions, gender and religious and cultural beliefs — plays a major role in shaping his personality. Noting that firstborn children generally get a lot of attention from their parents, Adler crowned firstborns as socially dominant, intellectual, conscientious and prone to perfectionism.

Since Adler, the debate over firstborn personalities has raged, as has the research, and most of it has only buttressed Adler’s initial perceptions.

American psychologist Kevin Leman, perhaps this country’s best-known expert on birth order, entitled his 2008 book on firstborns “Born to Win,” and in his 1998 book, “The Birth Order Book,” had this to say: “Firstborns are prepared, organized and ready to get things done.”

Adler also noted that the term “firstborn” is somewhat flexible. Firstborns, he argued, can include the oldest of a sex, those more than five years younger than an older sibling, and children who, for whatever reason, step in and assume the oldest child’s typical privileges and responsibilities.

Three years ago, Norwegian researchers added to the debate when they found that firstborn children had IQs an average of three points higher than their closest siblings, and credited the difference to family dynamics, not biological factors.

The study, like just about everything having to do with birth-order theories, has been challenged by skeptics, but it added to the predominant notion that firstborn children, in so many ways, have a leg up on their siblings.

In the meantime, other researchers and pop psychologists have added their two cents, pointing out that more than half of U.S. presidents have been firstborns, as were 21 of the first 23 astronauts, most entrepreneurs and most students at Harvard.

Patricia Roberts-Rose of Catonsville, mother of two girls, buys into the birth-order theories. Her 8-year-old, she says, is more outgoing, more independent and more confident than her 5-year-old. “You could leave her somewhere all day and she’d be OK,” says Roberts-Rose. “She’s changed schools a couple of times already and done absolutely fine. … It amazes me.”

Of course, not everything is rosy in the land of the firstborn. Eldest children, like the rest of the world, are not perfect.

Researcher Frank Sulloway, in his 1997 book “Born to Rebel,” added some provocative twists to standard birth-order theory. He argued that firstborn children, since they identify more strongly with authority figures, are more likely to be conformists defending the status quo — and less likely to be the creative driving forces behind cultural, social and scientific innovations.

Being the oldest sibling has plenty of other disadvantages as well, say the experts. All that parental attention, not to mention those high parental expectations, can add up to pressure to perform or succeed — pressure not put on younger brothers and sisters.

Parents also tend to be stricter with their first child, the experts say, as well as likely to give them more work. Whether the task is running out for a loaf of bread or cleaning up the kitchen, writes Leman, “the dependable firstborn is likely to get the assignment.”

Even the presumed strengths of the classic oldest child can have a negative flip side. A person who is organized can lack the flexibility or patience to cope with the real world. A person drawn to such precise careers as law, architecture or medicine may never give less stable careers as art, music or sales a chance. An ambitious, take-charge person can be overbearing or insensitive.

And then there is the perfectionist bugaboo, which can make a person endlessly critical of everyone — including himself.

In his “The Birth Order Book,” Leman writes: “Outstanding leaders and achievers they may be, but hard-driving firsborns often pay the price. If their bodies don’t break down, relationships with family or friends usually do.”

Gwen Mahoney, who teaches an education course called “The Parenting Process” at Towson University that covers birth-order theories, said much of the theories is simple common sense.

For example, she points out, “Since the oldest child is raised with adults only, at least at first, why wouldn’t they relate better to adults.”

Her students, Mahoney says, often can relate to at least some of the theories. “A lot of the firstborn students have pointed out that they thought they were parented much more strictly, and the younger ones got away with much more. I hear that all the time.” As a matter of fact, adds Mahoney, a mother of four, “my oldest daughter accuses me of that all the time.”

But even her students, hearing birth-order theories for the first time, realize they don’t explain everything, Mahoney says.

“Some will nod their heads rapidly, in agreement, but they they stop because they know it’s more complicated,” she says, and involves factors such as gender, spacing between children and a whole lot more. “Some will say, ‘Yeah, that sounds like my family,’ but it’s not across the board.

“To me,” adds Mahoney, “it seems like the empirical data on this is pretty weak.”

Mary Nalepa would second that notion. As much as she realizes that her oldest child fits the classic firstborn mold — besides her avid devotion to skating, Mackenzie is an honor student and natural care-giver to her siblings, especially the youngest — Mary sees the holes in the theories. For example, she notes, her second child, 10, is very different from Mackenzie, but her third, 8 and also a middle child, has many of the eldest’s qualities.

“You can see some validity to it (birth-order theory),” says Nalepa. “But sometimes you wonder whether what you’re looking for is what we see.”

PARENTING THE FIRSTBORN CHILD
• Go easy on the responsibilities. It’s a natural tendency to give the oldest child more chores and duties, including baby-sitting duties, and it’s sometimes necessary. But it also can be unfair.
• If you do hand out extra responsibilities to your firstborn, give her some extra privileges as well — a later bed-time, for example.
• Be wary of holding up your oldest as a role model for his kid brothers and sisters, and of expecting too much from them. That can be a lot of pressure.
• Give them special one-on-one time, even if it’s just running an errand together. Firstborns tend to respond better than other children to adults, plus they often believe their parents focus more time and energy on the younger children.
• Caution patience. More adept and able than their younger siblings, firstborns can be bossy. They need to learn to get over that.

FAMOUS FIRSTBORNS
• Barack Obama (and more than half of all U.S. presidents)
• Bill Cosby
• Winston Churchill
• Walter Cronkite
• Robert DeNiro
• Harrison Ford
• Rush Limbaugh
• Steven Spielberg
• Oprah Winfrey