A large-scale review of 30 studies involving nearly 20,000 participants suggests that parental favouritism is a common pattern across families.
The research found consistent trends in how parents interact with their children, with differences often linked to birth order, gender and personality.
Younger siblings were more likely to receive more warmth and less discipline, while older siblings tended to face stricter rules and higher expectations.
The review also found that daughters were slightly more likely to be favoured than sons. Across multiple studies, parents reported closer emotional relationships with daughters, including stronger communication and bonding.
Personality was identified as the most significant factor. Children described as agreeable, responsible or easier to manage were consistently rated more positively. Researchers found that personality differences accounted for a substantial portion of favouritism patterns, in some cases more than birth order or gender.
While the differences in treatment are often subtle, they can have measurable effects. Studies included in the review found that children who perceived themselves as less favoured were more likely to report symptoms of depression and anxiety, as well as lower self-esteem. Some research also linked perceived favouritism to increased risky behaviour and weaker family relationships later in life.
Perception plays a key role. In one study, more than 65 per cent of siblings agreed that one child was treated differently, even when parents did not report a preference.
Researchers note that favouritism does not typically appear as extreme or intentional behaviour. Instead, it is often reflected in small, repeated differences in attention, discipline and expectations over time.
The findings highlight how these patterns, while often subtle, can influence family dynamics and long-term outcomes for children.
