To illuminate how within-family differences in achievement may emerge, this study examined sibling experiences in middle childhood as predictors of sibling differences in college graduation. First- and second-borns from 152 families reported on their experiences with siblings and parents at ages 11.80 (SD = 0.56) and 9.22 (SD = 0.90),…

Vocabulary knowledge was tested in a native (Cantonese-Chinese) and foreign (English) language in 150 twins and 150 singletons aged 6-11 years, matched on age, gender, grade level, nonverbal intelligence, parents' education, family income, and number of siblings and household members. The singletons clearly outperformed the twins on the native…

Nonmaternal care of infant children is increasingly common, but there is disagreement as to whether it is harmful for children. Using data from 9,185 children (5 years and older) who participated in the Children of the National Longitudinal Survey of Youth, the current study compared 2 groups: those for whom nonmaternal care was initiated in the…

Retrospective studies indicate 2 major classes of autism spectrum disorder (ASD) onset: early and later, after a period of relatively healthy development. This prospective, longitudinal study examined social, language, and motor trajectories in 235 children with and without a sibling with autism, ages 6-36 months. Children were grouped as: ASD…

Compared pretend play enactment, negotiation, internal state language, and sibling relationship quality in 40 kindergartners with older or younger siblings. Found that frequent pretend play dyads used more high-level negotiation and internal state language than infrequent pretend dyads. Friendly relationship quality was negatively related to…

Compared attitudes, expectations, and behaviors of early adolescent girls with an adolescent childbearing sister to those of girls with nonchildbearing adolescent sisters. Found that the younger sisters of childbearing adolescents were consistently different from those of nonchildbearing adolescents on key characteristics known to be correlated…

Investigated birth-order differences in children's early vocabulary development. Compared the composition and age of acquisition of the first 50 and 100 words of 9 firstborns and their younger siblings, using a longitudinal maternal diary methodology. A small but significant birth-order effect was found for the age at which the 50-word milestone…

Examined association of three maternal regulating behaviors with children's positive and negative behaviors toward siblings in 40 Japanese families. Observed maternal regulating behaviors more frequently when younger sibling was still in early developmental stage. Older siblings' negative behaviors toward younger positively correlated with…

Examined influences on children's behavior problems in households defined by marital status and sibling relatedness. Found that genetic influences accounted for 81 to 94 percent of mean-level difference in behavior problems between two-parent/full sibling, and the mother-only/half sibling groups. Shared environmental influences accounted for 67 to…

Examined sex-typing in child personality, interests, and activities as function of traditionality of parents' gender role attitudes and sex composition of sibling dyads. Found that sex-typing was most evident in children's interests and activities. Differences in children's sex-typing as a function of fathers' attitudes and sibling sex…

The theory-of-mind abilities of twins, children with nontwin siblings, and only children were compared to investigate further the link between number and type of siblings and theory-of-mind abilities. Three- to 5-year-old children with nontwin siblings outperformed both only children and twins with no other siblings, twins who also had other…

Examined connections between having a sister versus a brother and coming from a same-sex versus an opposite-sex sibling dyad, and sex-typing in adolescents' friendships. Findings suggested that sisters may learn control tactics from brothers that they apply in friendships. Boys were less likely to model emotional intimacy. Coming from opposite-sex…

First- and fifth-grade only-children and children with siblings completed 11 cognitive tasks to investigate differences in cognitive abilities that may exist due to the Chinese 1-child family planning program. Superiority of grade one only-children over children with siblings appeared for memory processes, language skills, and mathematics.…

The IQ performance of children who experienced the birth of a younger sibling was found to drop 10 points during the next two years for singleton children and 5.8 points for last-born children from families of comparable size. The study controlled for sex, family size, age at assessment, and IQ before the birth of the sibling. (Author/RH)

Preschoolers did use certain aspects of the "child-directed speech" register: they addressed their infant siblings with a high pitch, with relatively short utterances, and with many directives and self-repetitions. However, linguistic interactions of preschool-age siblings and infants were different from those of mothers and infants in several…