Birth order can influence a person’s personality.

 Birth order can influence a person’s personality.

Over the past 125 years, many studies have documented significant birth-order differences, indicating the formative influence of birth order on a person’s personality. For example, one study suggests that while parents may encourage firstborn or only children to follow a more prestigious path, such as becoming a doctor or lawyer, they might take a more relaxed approach with later-born children, which can influence personality.

Of the first 23 American astronauts who made trips into space, how many were firstborn children?Of the first 23 astronauts who made trips into space, 21 of them were eldest or only children. In fact, all seven of the original Mercury astronauts were firstborns.

What percentage of CEOs are reportedly firstborns?A 2007 survey of corporate leaders conducted by an international organization of CEOs stated that 43% of CEOs were firstborns, 33% were middle-borns, and 23% were last-borns.

Which group may be more likely to engage in sports that involve physical danger?A study involving 67 firstborn and 99 later-born male college students found that, in general, later-borns are more likely to engage in dangerous sports than firstborns. The study compared the subjects’ preference for participation in such sports as judo, football, lacrosse, sky diving, ski jumping, and motorcycle racing, among others.

Researchers suggest which of the following as a reason only children may be reluctant to pursue outdoor careers?

•  Overprotective parents fear for their physical safety

This reflects the theory that, in general, parents may be more anxious about the activities of an only child, while parents of several children may have a more relaxed approach.

Among siblings, which group reports being more sentimental?

•  Younger siblings

A survey that asked 76 pairs of high-school-aged siblings to rate themselves on various personality aspects found that more younger siblings rated themselves as more sentimental and forgiving than their older siblings

Which group may contain more perfectionists?Older siblings

The same survey of 76 pairs of high-school-aged siblings found that more older siblings tended to state that they were perfectionists.

Researchers theorize that which of the following may be the reason younger siblings get better grades?

• They are tutored by their older siblings
• They are more competitive than their older siblings
• They learn about overcoming challenges by watching their older siblings
• All of the above

In a study of sibling relationships, researchers theorized that younger siblings are mentored by older siblings, feel the need to be more competitive, and have more confidence in overcoming obstacles because they’ve watched their siblings face those same challenges.

• The data did not include female children in the birth order

Francis Galton did not count female children in the data he used to write “English Men of Science: Their Nature and Nurture,” which was published in 1874. So Galton would have considered a male subject a firstborn even if he had five older sisters.

What is one of the primary reasons some scientists think decades of birth-order research is flawed?

•  Family size was not considered

Parental money and time are finite resources, and in larger families, these are spread thinner than in smaller families. Also, family size can be associated with several other variables, including ethnicity, education, and financial concerns.