12 surprising traits of middle-born kids and how birth order shapes personality, study finds

Experts have long debated how birth order shapes personality, with middle kids often at the center of the discussion.

Many believe where a child falls in the family influences their traits, from the responsible eldest to the pampered youngest.

Research has explored these patterns, suggesting that firstborns may have higher intelligence.

A new study reveals that middle children tend to be more honest, humble, and agreeable than their siblings, adding a fresh perspective to the conversation.

A December 2024 study offers new insights into the debate over how birth order affects personality, says Upworthy.

While past research has been mixed, with many experts believing birth order has little impact, people still link certain traits to being the oldest, youngest, middle, or only child.

However, a team of Canadian researchers who analyzed survey data from 700,000 adults found that middle children tend to be more honest, humble, and agreeable—essential traits for building strong relationships and working well with others.

What did the study find about middle kids?

The study used the HEXACO personality inventory, a popular test developed over the past 20 years, to measure key personality traits across cultures.

It focuses on six characteristics: honesty-humility, emotionality, extraversion, agreeableness, conscientiousness, and openness to experience.

Using this well-regarded assessment, researchers hoped to better understand whether birth order shapes personality.

“Most previous research had found that adults’ personality trait levels were unrelated to their birth order,” study authors Michael Ashton of Brock University and Kibeom Lee of the University of Calgary told PsyPost.

When researchers began collecting online personality data a decade ago, they included birth order in their survey to explore a broader range of traits than previous studies had examined.

Surprisingly, they found a connection between birth order and certain personality traits.

This discovery led them to add another question about family size, asking participants how many siblings they had, including themselves.

Middle kids and those from larger families scored higher in traits like Honesty-Humility and Agreeableness, according to the HEXACO framework.

The test found that people with high Agreeableness are more forgiving, less judgmental, willing to cooperate, and better at controlling their temper.

Those who score high in Honesty-Humility are less likely to manipulate others, show little interest in wealth or luxury, and don’t feel entitled to special treatment.

Middle kids ranked the highest in both traits, followed closely by the youngest. The eldest children scored the lowest, with only the children ranking near the bottom.

12 top qualities of middle children

Middle children often grow into adaptable, empathetic, and independent individuals thanks to their unique role in the family. These traits help many of them become natural leaders and strong communicators. And according to WebMD, here are the 12 qualities that often stand out the most.

1. They learn by watching older siblings or peers.

2. They develop strong social skills early.

3. They carve out their own identities.

4. They may feel overlooked and work harder to stand out.

5. They often grow into leaders, innovators, and changemakers.

6. They tend to be more open to taking risks (85% vs. 50% of firstborns).

7. They embrace new ideas easily.

8. They are strong communicators.

9. They see different perspectives and negotiate well.

10. They are empathetic and adaptable.

11. Their sense of individuality can drive innovation.

12. They often develop influential ideas and lead social movements.

Meanwhile, scientists are still debating whether birth order has a real impact on personality. Studies from 2019 and 2020 have produced mixed results, Parents noted.

The 2020 research found no proof that only children are more self-centered than those with siblings, while the 2019 study suggested that personality differences between people with and without siblings are barely noticeable.

Here’s some quick news discussing the latest study about the middle kids via The Project: