title: The relationship between twin language, twins' close ties, and social competence.
abstract: This study investigated the relationship between twin language, twins' close ties, and social competence in a prospective longitudinal study. We hypothesized that twins whose tie is close would be more likely to develop a twin language, and these twins would be less likely to develop social competence. In addition, we hypothesize that some environmental factors, such as having an older sibling, preschool attendance, zygosity, and sex are also related to twin language, twins' close ties, and social competence. At baseline in 1999 a mailed questionnaire survey was conducted, and a follow-up questionnaire was distributed in 2004 among 958 mothers. As a result, 516 respondents returned the questionnaire (53.9%). In this study, we used 261 twin pairs aged from 6 to 12 years (school-age children) for analysis, excluding those with missing values. In the present study, we found that zygosity and sex were associated with twins' close ties. Having an older sibling and preschool attendance did not affect the twins' close tie, twin language, or social competence. One of the most important findings was that social competence was not affected directly by twins' close tie, but was affected when a twin language was found.
authors: Department of Community Health Nursing, Graduate School of Nursing, Osaka City University, Osaka, Japan.
authors: Chisato
authors: C
authors: Hayashi
authors: Department of Health Promotion Science, Faculty of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.
authors: Hiroshi
authors: H
authors: Mikami
authors: Department of Nutrition, Harvard School of Public Health, Boston, MA, USA.
authors: Reiko
authors: R
authors: Nishihara
authors: Suita Municipal Health Center, Suita City, Osaka, Japan.
authors: Chiho
authors: C
authors: Maeda
authors: Department of Health Promotion Science, Faculty of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.
authors: Kazuo
authors: K
authors: Hayakawa
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D012919:Social Behavior; D011795:Surveys and Questionnaires; D014429:Twins, Dizygotic / Q000235:genetics* / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics* / Q000523:psychology