Young children with older sisters have better language skills than those with older brothers


Intuitively, it is tempting to think that a child who has an elder brother or sister will grow up in a stimulating linguistic environment and will develop their language skills faster than the family’s firstborn.

However, several studies have shown the contrary: the acquisition of language in a child with an elder sibling is reported to be slower than a child who has none.

What is even more surprising is that apparently only elder brothers impact the language skills of their younger siblings, as a study conducted by a research team from the CNRS, the AP-HP, the EHESS, the ENS and the INSERM has just shown.

The study finds that children who have grown up with an elder sister have identical development to children with no elder sibling.

More than 1000 children have been followed from birth to five and a half years old in the mother-child cohort EDEN*.

Their language skills were evaluated at 2, 3 and 5.5 years old by tests measuring several aspects of language, such as vocabulary, syntax and verbal reasoning.

Children who have an elder brother had on average a two-month delay in language development compared with children with an elder sister.

The scientists propose two hypotheses that may explain this result.

The first is that elder sisters, in being more willing to talk to their younger siblings than brothers, may compensate for their parents being less available. Another hypothesis would be that elder sisters compete less than elder brothers for parental attention.

The scientists propose two hypotheses that may explain this result.

The first is that elder sisters, in being more willing to talk to their younger siblings than brothers, may compensate for their parents being less available.

Another hypothesis would be that elder sisters compete less than elder brothers for parental attention.

Though this study cannot separate these two hypotheses, it does show that early language development in a younger sibling tends to be slower when the elder is a boy

For their next project, the scientists want to examine the impact of culture (specifically geographical origin) on these results.

*- The EDEN cohort recruited families between 2003 and 2006 in the CHU in Nancy and Poitiers.

Despite the constant decline in number of children in families, the ideal of the two-child family still persists (Testa, 2012) and it is generally assumed that siblings mutually enrich and learn from one another (Howe and Recchia, 2006). In the case of families from immigrant backgrounds, the assumption is furthermore that older siblings play an important role in integrating the family into the host culture and constitute a facilitator particularly to the language of the host country (Cooper et al., 1999Shin, 2002).

Language skills, which are the focus of the present study, cover semantic, syntactic, morphologic and pragmatic facets (Saxton, 2010) and are considered as a crucial prerequisite to be successful in and after school. Studies indicated that there is a gap between language skills of immigrant and non-immigrant children starting in early childhood, which does not close even after years of schooling (e.g., Oller and Eilers, 2002). Local language oftentimes implies a second language for immigrant children. Second language skills are acquired in a broad range of developmental contexts that include interactions with educators in early education institutions, with children and adults in the neighborhood as well as interactions within the family (Hoff, 2013). Research regarding familial contexts in the scope of second language acquisition has been sparse so far with existing studies mainly focusing on parental influences (e.g., Becker, 2010). However, empirical evidence of whether and how sibling structure variables are associated with second language skills of children is still pending.

Thus, the present study examines the effect of sibling structure variables on the second language skills of immigrant children. In particular, we investigated whether classic models of sibling structure variables such as the resource dilution model can be applied to second language acquisition. These research questions are addressed in a large sample of bilingual children in Switzerland.

The Resource Dilution Model

Educational studies of the past 50 years report that only children and children with fewer siblings achieve better grades at school and have a higher level of education than individuals from families with many children (e.g., Blau and Duncan, 1967Park, 2008). The resource dilution model explains this inverse relationship between number of siblings and number of years in education with a decrease in parental resources (Blake, 1981). This model is based on the assumption that parental resources are finite and have to be shared between children within a family. Every additional sibling means a reduction in the share allocated to each child, thus reducing one of the foundations of their intellectual development. According to Blake (1981), parental resources include material resources, extra-familial learning opportunities, and parental attention, intervention and teaching. The strength and the pattern of the relationship vary depending on the type of resource (Downey, 19952001). Some resources, such as a stock of books for example, can be shared between several siblings without any significant reduction in their value. By contrast, financial resources, invested by parents in a child’s extracurricular education for example, appear to be more vulnerable to the number of siblings (Downey, 19952001Steelman et al., 2002). According to the resource dilution model, parental resources available do not decline linearly with every additional child. Rather, the decline in parental resources as the number of children within a family increases comes closest to the theoretical equation y = 1/x (Downey, 1995), where x represents the total number of children in the family and y represents the parental resources available such as financial resources for early education institutions.

Effect of Number of Siblings

The effects of sibship size become particularly clear when measuring school success and education indicators such as number of school years (Blake, 1981Iacovou, 2007), but they can also be seen in studies on standardized intelligence and language measures (Belmont and Marolla, 1973Polit and Falbo, 1988Steelman et al., 2002Sundet et al., 2010). A comparison of non-verbal and verbal measures in Polit and Falbo’s (1988) review revealed a greater vulnerability in the field of language.

Research into sibling effects on second language acquisition is sparse. It therefore remains unclear whether and in which way the number of siblings is linked to the second language skills of bilingual children, and whether the effects of diminishing parental resources can be seen in a way that is analogous to first language development. Given a greater degree of direct interaction between parents and child in families with fewer children (Jones and Adamson, 1987), we assume that children from smaller families benefit more from parents’ knowledge of the local language (when extant) or indirectly gain a better foundation for acquiring a second language through better support in the first language (e.g., reading picture books together; Verhoeven, 1994Uchikoshi, 2006). Based on Downey’s (1995) finding that financial resources have a particularly strong tendency to dilute and the knowledge that children pose a risk of poverty (European Commission, 2008), we assume that families with many children have fewer financial resources to provide educational opportunities outside the family and therefore, the likelihood of a child attending early education institutions is lower.

As early education institutions constitute key places for the second language acquisition of immigrant children (Aukrust and Rydland, 2011Niklas et al., 2011Halle et al., 2012), we suppose that limited access to these institutions has a negative effect on the second language development, i.e., attendance in an early education institution is assumed to mediate the relationship between the number of siblings and second language skills. This mediational effect is all the more plausible as access to the early childcare system in Switzerland and some other European countries is limited and parental costs for institutional childcare are high (OECD, 2013).

Although knowledge to date suggests that an inverse relationship exists between the number of siblings and second language skills among bilingual children according to the resource dilution model, no evidence exists confirming this assumption. Ortiz (2009), for example, examined 747 Latino preschool children in the USA assessing English language skills by means of a standardized receptive language test. In Ortiz’s study, contrary to the author’s expectations, there was no association between the number of children and knowledge of English language skills.

Effect of Birth Order

During their early years of life — or at least their first year — first-born children do not have to share parental attention and financial resources for early education institutions with their younger siblings. Thus, based on the resource dilution model it can be assumed that first-born children have an advantage over later-born siblings during childhood. Various studies have shown that there are differences favoring first-born children both in regard to the onset of speech and in regard to level of language skills (Pine, 1995Zambrana et al., 2012). In Fenson et al.’s (1994) large-scale study first-born children showed greater abilities in word production in both infancy and toddlerhood. The Swedish study of Berglund et al. (2005) with over one thousand 18-months-old children revealed significant negative effects of birth order on both the production and the comprehension of words. However, the strength of these effects was minimal, with an explained variance of 1.7% in vocabulary production and 0.5% in vocabulary comprehension respectively. Based on a study with pairs of siblings, Pine (1995) showed that first-born children achieve the 50-word milestone roughly a month earlier than their second-born siblings. However, no significant differences were found for the 100-word milestone some months later. Differences in the amount and the kind of parental input were assumed to be the reason for the differences between first- and later-born siblings. Studies showed that first-born children are read to more often than later born children (Raikes et al., 2006Westerlund and Lagerberg, 2008), that these children receive more linguistic input from their mothers, and that the children are more often explicitly encouraged to express themselves (Jones and Adamson, 1987Hoff-Ginsberg, 1998).

Although some studies revealed a negative effect of birth order, there are also studies, that found no differences in standardized language tests or even suggested that later-born children are at an advantage (Jenkins and Astington, 1996Oshima-Takane et al., 1996Hoff-Ginsberg, 1998Bornstein et al., 2004Westerlund and Lagerberg, 2008). For example, Oshima-Takane et al. (1996) showed that later-born children used personal pronouns earlier, which the authors attributed to more frequent triadic interactions with the mother and the elder sibling. Hoff-Ginsberg (1998) reported disadvantages in vocabulary and grammar in later-born children, but also noted a developmental advantage in conversational skills.

The extent to which birth order is associated with second language skills among immigrant children remains unclear. On the one hand, it is conceivable that mechanisms similar to those in monolingual children are at work, and that higher second language skills can be expected in first-born children during their first few years due to their situation as only children. On the other hand, it has been repeatedly reported that older siblings constitute a facilitator to the local language (e.g., Shin, 2002) and that second-born children accordingly have been expected to experience more favorable conditions of acquisition and have better second language skills. This advantage might be particularly true for children with an older sibling in school age. To become an effective language partner, older siblings need to possess a certain level of second language skills. In school age, children improve their second language skills und thus pose a significant source of language exposure to the younger sibling (Bridges and Hoff, 2014). Moreover, at school, older siblings learn the importance of local language skills and bring that knowledge into the home. Younger siblings might profit from the insights and second language skills of their older siblings and thus, improve their local language skills (Wong Fillmore, 1991Shin, 2002).

These two approaches — the resource dilution model as well as elder siblings as facilitators for the second language acquisition of their younger siblings — explain the issue on different levels and are not mutually exclusive. Thus it is conceivable that while the processes of interaction between siblings benefit learning, the arrival of an additional sibling changes the relationship constellation and the financial situation of a family to such an extent that the second-born child is placed at a developmental disadvantage.

To date, evidence for both lines of arguments is sparse and mixed. Ortiz (2009) assumed better second language skills for later-born children, but failed to demonstrate evidence in a group of Latino preschool children in the USA. No effect of birth order on knowledge of the second language emerged either in David and Wei’s (2008) longitudinal study with 13 French- and English-speaking children nor in Caspar and Leyendecker’s (2011) study with 88 Turkish-German-speaking children. Bridges and Hoff (2014) also examined older siblings’ influence on language skills in a total of 87 English–Spanish bilingual toddlers in the USA assessing English and Spanish language skills using caregiver report measures. In contrast to the previous findings, in their study, children with an older sibling showed more advanced English language skills. Moreover, bilingual children with an older school-aged sibling were more skilled in English.

In sum, the current state of research is marked first by a lack of studies on sibling structure variables among immigrant children and, second, by mixed results. Thus, further studies are needed to shed light on the significance of siblings on second language skills of bilingual children.

The Current Study

The current study examined the extent to which three sibling structure variables, — i.e., number of siblings, birth order and presence of an elder sibling at school age — are connected to the second language skills of bilingual children, and whether the resource dilution model can be adopted to the second language acquisition of immigrant children. First, we postulated an inverse relationship between the number of siblings and second language skills. Second, we examined whether attending an early education institution mediates the relationship between number of siblings and second language skills referring to the resource dilution model (Blake, 1981Downey, 19952001). Third, we examined whether, in analogy to studies on early first language development, better second language skills can be expected of first compared to later-born children (e.g., Zambrana et al., 2012), or whether, conversely, later-born children benefit from their older siblings and show higher levels of second language skills (e.g., Shin, 2002Zambrana et al., 2012). To complement the third hypothesis, we examined whether the effect of the birth order depends of the age gap to the older sibling. We assumed that later-born children have higher levels of second language skills if the older sibling is already at school age and can thus be expected to possess better German and better communication skills (Bridges and Hoff, 2014).

Media Contacts:
Francois Maginiot – CNRS
Image Source:
The image is in the public domain.

Original Research: Closed access
“The Effect of Older Siblings on Language Development as a Function of Age Difference and Sex”. Naomi Havron et al.
Psychological Science doi:10.1177/0956797619861436


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