Lead author Alexander Jensen, PhD, is an associate professor at Brigham Young University, and he explained, “For decades, researchers have known that differential treatment from parents can have lasting consequences for children.”

“This study helps us understand which children are more likely to be on the receiving end of favouritism, which can be both positive and negative.”

The research, which was published in the journal Psychological Bulletin, revealed that parents may be more inclined to favour children who are agreeable and conscientious, and more often, they are the daughter.

The research examined the link between children’s characteristics and differences in how their parents treat them. Of the personality traits evaluated, children who were conscientious also appeared to receive more favourable treatment.

The researchers initially thought that mothers would tend to favour daughters and fathers would favour sons. However, the study found that both mothers and fathers were more likely to favour daughters.

Jensen determined that a parent’s favouritism for one of a child is often based on birth order, gender, temperament and personality traits — such as extroversion, agreeableness, openness, conscientiousness and neuroticism.

“Understanding these nuances can help parents and clinicians recognise potentially damaging family patterns,” he explained. “It is crucial to ensure all children feel loved and supported.”

“So, the next time you’re left wondering whether your sibling is the golden child, remember there is likely more going on behind the scenes than just a preference for the eldest or youngest. It might be about responsibility, temperament or just how easy or hard you are to deal with,” he said.