Sibling bullying refers to any unwanted aggressive behavior by a sibling, which is featured by an observed or perceived power imbalance and repetitiveness (Wolke and Samara, 2010; Wolke et al., 2015). Sibling bullying is a common incident in childhood and adolescence within households worldwide (Khan and Cooke, 2013; Yu et al., 2017). According to a systematic study, nearly 50% of children are involved in sibling bullying every month, and 16–20% experience sibling bullying several times a week (Menesini et al., 2011; Wolke and Skew, 2012). Though sibling bullying is usually considered by parents or researchers as a normal or harmless phenomenon (Kettrey and Emery, 2006; Dale et al., 2014), there is ample evidence to support that sibling bullying can predict a number of internalizing and externalizing problems in childhood or early adulthood, which include depression, anxiety, self-harm behavior, and even suicide (Bowes et al., 2014; Jasmin and Anat, 2018; Foody et al., 2020). Sibling bullying was associated with clinical diagnosis of depression and suicidal ideation as well as suicidal self-harm (Dantchev et al., 2019; Sharpe et al., 2021).

However, compared with the volume of studies conducted in the western countries (Dantchev and Wolke, 2018; Dantchev et al., 2018), there are a paucity of studies with regard to aggressive behavior between siblings in the East (Yu et al., 2017), especially in China. Few is known about the characteristics of sibling bullying in this one of the most populous countries. With the one-child policy have been replaced by the two-child policy since 2011, there is an increasing number of families with two or multiple children in both rural and urban areas of China (Zeng and Hesketh, 2016). Therefore, it is necessary to understand the prevalence or factors relating to sibling bullying among Chinese population.

Family climate is the primary environment in where children interact with their sibling(s) (Wolke et al., 2015). According to family systems theory, family members are interdependent and can affect one another in a mutual and continuous way (Feinberg et al., 2012). Moreover, from a perspective of social learning theory, behavior learning of children can occur through direct experience or indirect observation of others’ behavior (Goodman et al., 2015). Several existing studies have identified significant associations between sibling bullying and family environmental factors, which were generally categorized into three categories: family structure, socioeconomic factors, and parental behavior (Wolke et al., 2015). Family structural factors generally include family composition (Tucker et al., 2014a), number of siblings (Tippett and Wolke, 2015), sibling’s gender (Menesini et al., 2011), age difference between siblings (Tucker et al., 2013), and birth order (Zeng and Hesketh, 2016). The resource control theory suggests that social group (for example, family systems) asymmetry may foster competitive behavior for social resources (Hawley, 1999), Siblings who are very asymmetrical in family structure, such as age, size, sex, birth order, abilities and so on, may provoke sibling conflict or sibling bullying in order to access to limited parental resources (e.g., affection, attention, and material goods) (Toseeb et al., 2020). For example, when a new sibling was born in the family, the first-born child may face the risk of losing some parental resources and then perpetrate sibling bullying in order to regain parental resources (Toseeb, 2021). Socioeconomic factors include family income (Eriksen and Jensen, 2009), parental education (Dantchev et al., 2018), and other characteristics that can represent socioeconomic status of household (Wolke et al., 2015). Research has shown that low-economic status was associated with sibling victimization, and economic hardship and a lack of financial resources were associated with greater physical aggression between siblings (Hardy, 2001). High socio-economic parents usually require more cooperative behavior among siblings, and they are particularly sensitive to sibling bullying and more likely to inhibit it effectively (Tucker et al., 2013). Parental behavior mainly include parental violence and parent–child violence (Button and Gealt, 2010; Radford et al., 2013). Studies have suggested that children may imitate the behavior patterns (e.g., aggression behavior) of their family members (Bandura, 1978), and children who witness or experience violence against parent or sibling (parent assault of a sibling) were at greater risk of becoming victims of sibling bully (Renner et al., 2020).

Apart from these family characteristics, there are other factors within household may also have effect on sibling bullying, such as parental absence and son preference, which root from the social and cultural background of the oriental countries. In China, there are over 61 million left-behind children, who have being left behind in home by one or both parents who migrate for economic reasons (Zhao et al., 2015; Chen and Ling, 2016). Previous studies had indicated that parental absence has strong links to psychological and behavioral problems of children (Zhao et al., 2014; Guo et al., 2015). Another potential factor that differs from the traditional context of the West is son preference. Chinese couples, particularly those in rural areas, still have historically a strong son preference, which refer to parents value sons more than daughters (Murphy et al., 2011). The different position of boys and girls within the family is reflected in such a Chinese traditional saying, “a son keeps incense at the ancestral alter burning” while “raising a daughter is like pouring water to other people’s field” (Shi, 2009). Therefore, son preference generally plays a sizeable impact on parents’ treatment of their offspring and often results in discriminatory behavior toward girls, which may motivate aggressive behavior between sons and daughters (Hesketh et al., 2011; Volk et al., 2012).

Current studies have shown that sex differences in sibling bullying with mixed results. Researchers have found that boys reported higher acceptability of sibling bullying as well as more likely to be involved in perpetrating sibling bullying than girls (Zhao et al., 2014), and girls have a higher rate being victims of sibling bullying (Button and Gealt, 2010). Some studies have also found no sex differences in sibling bullying (Wolke and Samara, 2010). Further work is needed to better understand this issue.

To the best of our knowledge, there is little research has assessed the association between sibling bullying and home environment based on Chinese population. What’s more, there are several family characteristics that may be associated with sibling bullying have not been explored, including parental absence and son preference. Therefore, the current research focused on the association between family factors and sibling bullying by a cross-sectional approach among Chinese adolescents, and explore sex differences in sibling bullying in the context of Chinese culture.

This is the first study to investigate the prevalence of sibling bullying based on the sample of Chinese children and adolescents. Over a quarter of children and adolescents were involved in sibling bullying in the last 6 mouths, and most of them were bully-victims. The finding is consistent with the previous studies which suggested that being both a victim and perpetrator was the most frequent role of sibling bullying involvement (Wolke and Skew, 2012; Jasmin and Anat, 2018). The possible explanations could include: first, the change of roles in sibling bullying involvement might owing to a fluid power dynamic that siblings usually gain more resource than each other by their familiarity (Wolke et al., 2015). Moreover, due to it is hard for victims to escape from sibling bullying behavior, conversely, they may act aggressive behavior against their siblings to protect themselves in the way learning from sibling’s perpetration.

This study found that boys were at greater risk of being pure victims in sibling bullying. There were no gender differences in pure bullies and bullying-victims. This is inconsistent with previous studies that boys were more likely to be bullies in the sibling bullying (Ersilia et al., 2011; Toseeb et al., 2020). This may be related to the different cultures. In the Chinese cultural context of collectivism and son preference, boys are more likely to be overprotected or coddled by their parent, which may inhibit boys’ aggression at home. This requires further cross-cultural research.

According to the combination of family systems theory and social learning theory, family environment plays an important role in children’s growth and development (Dantchev et al., 2018). In the study, family composition is a predictor of sibling bullying.

Consistent with previous research that age differences and birth order had the same effect on boys and girls (Tucker et al., 2013). But we were surprised to find that there are a lot of gender differences in the influence of family structure on sibling bullying.

First of all, those children living with a single parent were at greater odds of being pure bullies for boys, and pure victims for girls. The finding is in contrast to the prior work, which reveal that living in a single-parent family or a stepfamily has no significant association with aggressive behavior between siblings (Wolke et al., 2015). The inconsistency could be interpreted from different family composition of participants between the West and China. Tucker et al. (2014b) found that over one fifth of children live with a single parent in western countries, while the percent is far more than that in China from the present study (4.2%).

The second, parental absence is a risk factor of sibling bullying, and being left behind by both father and mother is related to being pure bullies and bully-victims for boys and pure victims for girls. Existing studies have found that long-term parental absence is associated with poor well-being of children because of inadequate family bonding, emotional vulnerability, and exposure to violence (Givaudan and Pick, 2013; Amato and Anthony, 2014), and left-behind children are at greater risk of psychological abuse and neglect, mental health problems, and behavioral problems (Eriksen and Jensen, 2009; Button and Gealt, 2010). The finding of this study extends our understanding of adverse status of left-behind children. Therefore, it may be practical to reduce sibling bullying among left-behind children by giving sufficient care and supervision from their parents.

The third, children whose sibling was a brother had higher odds of being all three roles of sibling bullying involvement for boys, and pure victims for girls. Consistent with the previous studies that brother–brother sibling were more likely to experience multiple incidents (Tucker et al., 2013), and girls with a male siblings are at higher risk of being victims (Menesini et al., 2011). These sex differences may show that boys are more aggressive, competitive, and sensitive to each other’s status, studies have shown more tensions between males (Zhang, 2020). While girls are raised to be easy-going and may be seen as a easy target of bullying in the family (Liu et al., 2021).

In our study, overall economic factors play a relatively small role in the impact of sibling bullying, but children living in economically disadvantaged families may indeed experience a greater risk of sibling bullying. Boys from poor-income families were at higher risk of being victims than those from medium-income families. Girls living in rural areas were at greater odds of being bully-victims than those living in urban. This is consistent with previous research that children from low-income families were more involved in sibling bullying (Bowes et al., 2014). Parents of low-income families were busy making a living and pay less attention to their children (Kochanova et al., 2022), which increases the likelihood of children being bullied by others or sibling due to the lack of parental supervision. Especially for girls in rural China, who have been taught from an early age to take responsibility for their families and be humble to their fellow family members, they are more likely to become victims of sibling bullying. Of course, they may also bully their sibling for limited parental resources.

Within three aspects of family environment, parental behavior have the most robust link to sibling bullying. Consistent with prior findings (Tucker et al., 2014a; Tippett and Wolke, 2015), both parent–parent violence and parent–child violence can predict greater risk of sibling bullying involvement, though girls were only at higher odds of being a pure victim compared with those girls who reported neither victimization nor perpetration. Conflict and aggression between parents as well as between a parent and a child could build a insecure climate within household (Zeng and Hesketh, 2016), which may lead to poor sibling relationship and even aggression between siblings (Piotrowski et al., 2021). This finding has a important implication for intervention of sibling bullying, which is that anti-bullying programs at home should not only help to improve sibling relationship but also take account of building harmonious parent–parent and parent–child relationship at the same time.

Son preference is a risk factor of sibling bullying. Surprisingly, those boys whose parents overtly value sons more than daughters were at greater risk of being a pure victim but were not more likely to be a pure bully compared with those boys whose parents had no behavior of son preference. What’s more, for girls, son preference increased odds of being all roles of sibling bullying involvement. The interesting finding may comes from two aspects. First, parental son preference would break the balance of sibling relationship and increase unequal interaction between boys and girls within household. Second, different parental treatment for sons and daughters may motivate those girls to perpetrate bullying behavior toward their brothers for obtaining sufficient resources and improving her status at home. Parents’ preference for sons is common in countries in East Asia through South Asia, to the Middle East and North Africa. In China, son preference stems from deep-rooted Confucian values and patriarchal family systems (Das Gupta et al., 2003), which could lead to discrimination against girls and neglect of health care and nutrition (Guo et al., 2015). Besides, the present study provides a new insight into negative influence of son preference, and indicates the significant association between parental son preference and sibling bullying of children.

Despite the potential contributions to the knowledge of sibling bullying, there were several limitations of the study. First, the cross-sectional nature limits our study to draw causality between sibling bullying and risk family characteristics. Second, this is a exploratory study to examine the association between sibling bullying and son preference, and we have not comprehensively control the potential effect of sibling dyad. Future studies should exclude brother–brother and sister–sister sibling dyad and further explode whether there is gender difference in the association among the children who have only one opposite-sex sibling. Finally, the study was conducted in a limited geographical setting. The extent to which this sample represents is also unclear, because information of respondents was only collected from children and adolescents in Hunan Province, central China. Future studies can further increase the sample size and recruit a national representative sample from different regions of China.

In this study, we first explored family factors of sibling bullying in the context of eastern tradition and culture by using a large sample of Chinese children and adolescents. Our findings indicate that a number of people have experienced sibling bullying perpetration, sibling bullying victimization in this adolescent sample. Boys are at greater risk of becoming victims. The prevalence of sibling bullying indicates that bullying behavior between siblings has become an important public health issue with the implement of the two-child policy in China. Most important, the findings contribute new information about the association between sibling bullying and family environment, and we explore sex differences in sibling bullying in the context of Chinese culture. Furthermore, the study has practical implications for intervention of sibling bullying in China. Specifically, preventive efforts should be aimed at those children who live in the family with a single parent, parental absence of both father and mother, a male sibling, a sibling closing in age, parent–parent violence, parent–children violence, and son preference. This highlights the need for parents and health professionals to educate these children to learn to control behavior, and establish healthy and positive sibling relationships. At the same time, it is necessary to encourage their parents to eliminate son preference and construct a harmonious and positive family environment.

The original contributions presented in this study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

The studies involving human participants were reviewed and approved by the Ethical Committee of Xiangya School of Public Health, Central South University. Written informed consent to participate in the study was provided by the participants’ legal guardian/next of kin.

ZQ and XL: study the conception and design. ZQ: data collection and draft manuscript preparation. YM: analysis and interpretation of results. All authors reviewed the results and approved the final version of the manuscript.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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