They say that the oldest child is the smartest, the middle child is overlooked, the youngest child is the family jewel, and the only child is spoiled.

But is there any truth to these speculations?

Psychologist Richard Mancina says yes—and no.

“You do see those [characteristic] patterns,” Mancina said.

“Birth order is part of [development]. But the situation of the family can also make a large difference.”

One pattern researchers have taken interest in is intelligence—is the oldest child really smarter?

“In many families, the firstborn is going to get into Harvard and the second-born isn’t,” Frank Sulloway, a psychologist at the University of California, Berkeley, said in “The Power of Birth Order” featured in the October 2007 issue of Time magazine.

Norwegian researchers concluded that the oldest children’s IQ’s are on average three points higher than those of their younger siblings.

However, in an article from American Psychologist in June 2000, other researchers reported on a study known as the “National Longitudinal Survey of Youth,” which contradicts this idea.

They studied each child in a large sampling of different families so that their conclusions were based solely on the comparison of children in a specific family, as opposed to a younger child of one family compared to an older child of a completely different family.

Conclusions showed that there was no pattern in IQ between younger and older siblings, contradicting previous studies.

Smarts aside, researchers have observed specific characteristics of the oldest child.

Because of the large amount of attention firstborns receive as babies, they usually strive throughout their lives to maintain their parents’ approval. This makes firstborns natural leaders. Over half of U.S. presidents were firstborns.

However, this trailblazer state of mind also contributes to more controlling and perfectionist firstborns.

The child following the firstborn is usually the polar opposite of his or her older sibling.

Middle-born children tend to be much more involved in friends or activities, because they don’t hold a unique place in the family—they are neither the firstborn nor the baby.

“Because the middle child feels that the world pays him [or her] less attention, he [or she] tends to be secretive,” Rome Neal, author of “Personality Traits Linked to Birth Order” featured on CBS’s “The Early Show” in June 2002, said.

“[Middle children] can usually read people well; they are peacemakers who see all sides of a situation; they are independent and inventive,” Neal said.

The babies of the family are usually more outgoing and gregarious.

Some youngest children have turned this trait into a gold mine. Humor gurus Jim Carrey, Steve Martin and Billy Crystal are all the youngest of their families.

However, since youngest children are more juvenile, they usually get more attention from their parents. Because of this they can be spoiled or manipulative.

“Younger siblings are looser cannons, less educated and less strapping, perhaps, but statistically likelier to live the exhilarating life of an artist or comedian, an adventurer, entrepreneur, GI, or firefighter,” Jeffrey Kluger, author of the book “The Power of Birth Order,” said.

Although only children have the potential to be spoiled or manipulative, research shows that that is not always the case, according to psychologist Kevin Leman.

Actually, only children are often more confident because they don’t have to compete for parental attention.

They also tend to get along well with older people, but they may have more difficulty interacting with people their own age because they aren’t around them at home.

“Only children are super first-borns. Everything we say about first-born children—reliable, conscientious, list makers, don’t like surprises—put the word ‘very’ in front of all those adjectives and you’ve got the only child summed up,” psychologist Richard Leman said in “How Birth Order Affects Your Personality.”

Although there is some criticism of birth-order research, it has become increasingly intriguing to scientists, and research continues.