Sibling relationships are understudied, and the research on adult siblings is more limited than for other family relationships. Yet, sibling relationships are often the longest lasting family relationship in an individual’s life due to concurrent life spans, and indeed, around 75% of 70-year olds have a living sibling (Settersten, 2007). Some suggest that sibling relationships play a more meaningful role in well-being than is often recognized (Cicirelli, 2004). The available evidence suggests that high quality relationships characterized by closeness with siblings are related to higher levels of well-being (Bedford & Avioli, 2001), whereas sibling relationships characterized by conflict and lack of closeness have been linked to lower well-being in terms of major depression and greater drug use in adulthood (Waldinger, Vaillant, & Orav, 2007). Parental favoritism and disfavoritism of children affects the closeness of siblings (Gilligan, Suitor, & Nam, 2015) and depression (Jensen, Whiteman, Fingerman, & Birditt, 2013). Similar to other family relationships, sibling relationships can be characterized by both positive and negative aspects that may affect elements of the stress process, providing both resources and stressors that influence well-being.
Siblings play important roles in support exchanges and caregiving, especially if their sibling experiences physical impairment and other close ties, such as a spouse or adult children, are not available (Degeneffe & Burcham, 2008; Namkung, Greenberg, & Mailick, 2017). Although sibling caregivers report lower well-being than noncaregivers, sibling caregivers experience this lower well-being to a lesser extent than spousal caregivers (Namkung et al., 2017). Most people believe that their siblings would be available to help them in a crisis (Connidis, 1994; Van Volkom, 2006), and in general support exchanges, receiving emotional support from a sibling is related to higher levels of well-being among older adults (Thomas, 2010). Relationship quality affects the experience of caregiving, with higher quality sibling relationships linked to greater provision of care (Eriksen & Gerstel, 2002) and a lower likelihood of emotional strain from caregiving (Mui & Morrow-Howell, 1993; Quinn, Clare, & Woods, 2009). Taken together, these studies suggest the importance of sibling relationships for well-being across the adult life course.
Gender Differences
The gender of the sibling dyad may play a role in the relationship’s effect on well-being, with relationships with sisters perceived as higher quality and linked to higher well-being (Van Volkom, 2006), though some argue that brothers do not show their affection in the same way but nevertheless have similar sentiments towards their siblings (Bedford & Avioli, 2001). General social support exchanges with siblings may be influenced by gender and larger family context; sisters exchanged more support with their siblings when they had higher quality relationships with their parents, but brothers exhibited a more compensatory role, exchanging more emotional support with siblings when they had lower quality relationships with their parents (Voorpostel & Blieszner, 2008). Caregiving for aging parents is also distributed differently by gender, falling disproportionately on female siblings (Pinquart & Sorensen, 2006), and sons provide less care to their parents if they have a sister (Grigoryeva, 2017). However, men in same-sex marriages were more likely than men in different-sex marriages to provide caregiving to parents and parents-in-law (Reczek & Umberson, 2016), which may ease the stress and burden on their female siblings.
Race-Ethnicity and SES Heterogeneity
Although there is less research in this area, family scholars have noted variations in sibling relationships and their effects by race-ethnicity and socioeconomic status. Lower socioeconomic status has been associated with reports of feeling less attached to siblings and this influences several outcomes such as obesity, depression, and substance use (Van Gundy et al., 2015). Fewer socioeconomic resources can also limit the amount of care siblings provide (Eriksen & Gerstel, 2002). These studies suggest sibling relationship quality as an axis of further disadvantage for already disadvantaged individuals. Sibling relationships may influence caregiving experiences by race as well, with black caregivers more likely to have siblings who also provide care to their parents than white caregivers (White-Means & Rubin, 2008) and sibling caregiving leading to lower well-being among white caregivers than minority caregivers (Namkung et al., 2017).
Directions for Future Research
Research on within-family differences has made great strides in our understanding of family relationships and remains a fruitful area of growth for future research (e.g., Suitor et al., 2017). Data gathered on multiple members within the same family can help researchers better investigate how families influence well-being in complex ways, including reciprocal influences between siblings. Siblings may have different perceptions of their relationships with each other, and this may vary by gender and other social statuses. This type of data might be especially useful in understanding family effects in diverse family structures, such as differences in treatment and outcomes of biological versus stepchildren, how characteristics of their relationships such as age differences may play a role, and the implications for caregiving for aging parents and for each other. Moreover, it is important to use longitudinal data to understand the consequences of these within-family differences over time as the life course unfolds. In addition, a greater focus on heterogeneity in sibling relationships and their consequences at the intersection of gender, race-ethnicity, SES, and other social statuses merit further investigation.