This study used nationally representative data on 59,096 South Korean adolescents. We examined the association of diverse family structures with health behavior, mental health, and PAA among adolescents. Adolescents from two-parent families had the highest PAA and those from restructured families had the lowest. Also, in the low-PAA group, the proportion of adolescents increased in the order of two-parent families, single-mother families, single-father families, and restructured families. These findings suggest that family structure could be a risk factor that might have negative effects on adolescents’ academic achievements, especially those from non-intact families. These findings are consistent with previous studies that reported associations between poor academic achievement and non-intact families [30, 31, 33, 39]. Adolescents need parental support for their school-related demands, including academic performance, which is closely related to the family structure [40]. However, single parents may have less time to devote to their children's school lives than two-parent households due to the many social demands. In fact, children from non-intact families receive less academic encouragement and support on average than those from two-parent families [41, 42].
We found an increasing gradient of OR from two-parent family to restructured families in “smoking,” “using e-cigarettes,” “drinking,” “sexual experience,” after adjusting for gender, age and perceived family economic status. These findings suggest that the level of risk factors affecting the health behavior of adolescents might differ depending on the family structure, and that it is necessary to better understand the association between diverse family structures and health. Our results are consistent with previous studies showing that adolescents in non-intact families are more exposed to the risk of poor health behaviors and mental health [11, 15, 43, 44]. Previous studies reported that good parent-child communication partially reduced smoking, drinking, and drug use [11]. Substance use in adolescents has been found to have a more dangerous association in single-father families than in single-mother families, which can be attributed to the differences between fathers and mothers. Fathers tend to spend less time at home with their children and are more likely to be at work than mothers [2], and mothers are more interested in their children's daily lives [45] and are more likely to advise them on health issues such as substance use [46]. In terms of parent-child communication, fathers exhibited worse communication than mothers [11]. Previous studies reported that sexual behavior was more related to negative events than to family structure or income. The experience of negative events and sexual behavior in each family structure may need to be further studied later [43, 47]. The poor mental health of adolescents from non-intact families can be understood from various perspectives. Compared to their peers, they have few economic resources [4, 48], lack opportunities to participate [49] in leisure activities, and struggle with the school curriculum, risk of being exposed to bullying; this is higher in single-parent and restructured families than in two-parent ones [6, 44, 50]. Exposure to bullying and violence can affect mental health and lead to behavioral problems [51].
We found that in the categories of smoking, drinking, sexual experience, depression, suicidal ideation, stress, and poor perceived health, reconstructed families had a stronger relationship than the other family structures. Previous studies have reported that restructured families are likely to suffer from interpersonal difficulties such as parental conflicts compared to other families, including single-parent families, and are exposed to domestic violence and abuse [44, 52, 53]. Also, there may be tension among the children of different parents [54]. Elucidating the differences in the physical and mental health of adolescents among these family structures will help to better understand adolescents and establish strategies for health promotion intervention.
In our study, non-intact families were more associated with Internet use (more than two hours/week) than two-parent families. This result is consistent with previous studies showing that Internet addiction is higher in single-parent families than two-parent ones [14]. Our study found that single-father families were more closely associated with Internet use than single-mother ones, but a previous study reported that when parents and adolescents had a very bad relationship, the mother factor was more associated with Internet addiction than the father factor [14]. Also, negative emotions such as depression, anxiety, and feelings of inferiority that adolescents in non-intact families usually felt were associated with the risk of Internet addiction when accompanied by academic stress [55]. Since our study measured “Internet use” based on time spent online, our results need to be interpreted carefully when judging addiction. A further study on the relationship between family structure and Internet use and addiction is likely needed. The present study showed that the association of family structure with physical activity and obesity was not significant, and this is consistent with a previous meta-analysis study [12] that found no evidence that children of single-parent families need special measures to improve their physical activity levels. Also, in our study, single parents had a lower level of education than two-parent households, and previous studies reported that parents' low level of education is related to adolescents being overweight [15]. The relationship between family structure and obesity is likely to require further research.
We found that health behaviors and mental health were closely related to PAA even after adjusting for the family structure. A previous study reported that up to 24% of PAA variables were explained in relation to health behavior and academic achievement even after controlling family structure [56]. Our findings were consistent with a previous study that reported that the use of tobacco and alcohol were related to poor academic achievement [57]. According to problem behavior theory, both substance use and poor academic achievement are caused by similar fundamental psychogenic and social risks [58]. The pre- and post-relationship between substance use and poor academic achievement is difficult to fully understand, but most studies agree that substance use and poor academic achievement are in a negative relationship. [57, 59]. Our study supports a previous study that reported a link between Internet addiction and low academic performance [60]. Also, our study found an association between low PAA and sexual experience. This result is consistent with a previous study that reported that adolescents who engage in sexual intercourse at an early age may undergo a change in attitude, including a decrease in interest in academic activities [61].
In our study, depression, suicidal ideation, high perceived stress, and poor perceived health were associated with low PAA. A previous cohort study reported that academic achievement had a positive correlation with good mental health, hope, life satisfaction, and self-worth [62]. In addition, other previous studies reported that academic performance and poor mental health were negatively related, and that experienced stress was a barrier to academic performance [62, 63]. Our study found a relationship between perceived health and low PAA. In a previous study, the association between perceived health status and academic performance was not significant [63]. This association needs to be further studied. In our study, non-intact families were associated with low PAA compared to adolescents from intact families. Future plans for most non-intact families included the children's social and educational success and survival. However, those in a socially difficult situation may not be able to plan for their future, resulting in them neglecting their studies and becoming less motivated because they must focus on meeting their current needs [7]. A lack of motivation and awareness was associated with low academic achievement [57].
A clear linear gradient was observed when gender, age and perceived family economic status were adjusted, and linear gradient was maintained when health behaviors and mental health were added. Previous studies reported several reasons for the association of non-intact families with low academic achievement. Adolescents from non-intact families have a lower SES than those from two-parent families, and SES is an important factor in predicting academic achievement. Also, emotional support, encouragement, assistance, and homework support from parents are associated with adolescents’ good academic performance, with adolescents from non-intact families generally having less access to these social resources than those from intact families [33, 64, 65].
The strengths of this study are as follows. First, to the best of our knowledge, this study is meaningful in being the first to make use of nationally representative data on South Korean adolescents to understand their health behaviors, mental health, and PAA by family structure. Second, our study specifically examined the relationship between family structure as a social determinant of health and health behavior, mental health, and PAA, and the findings regarding these relationships are detailed and comprehensive. These results can thus serve as evidence for prioritizing health education for adolescents and will help set the direction of research related to family structure in the future. Our study has limitations that should be considered. First, this study was a cross-sectional one; thus, causal inferences could not be determined. Further longitudinal studies must be conducted to understand the potential ways that family structures may affect the lives of adolescents. Second, because the study utilized secondary data, we were unable to select variables of interest. Among non-intact families, whether parents have custody or not could affect children, but our study did not distinguish custody. Further research is needed that considers detailed classifications in order to understand single parents more deeply. Third, there may have been some self-expression bias because this study was based on self-reporting.