Sibling relatedness and pubertal development in girls and boys: A population-based cohort study.

ABSTRACT

PURPOSE: To investigate the association between sibling relatedness and pubertal development in girls and boys. METHODS: This cohort study consisted of 10,657 children from the Puberty Cohort, Denmark. Information on sibling relatedness was obtained by self-report. Information on pubertal markers was obtained half yearly from age 11 and throughout puberty. Mean age difference at attaining pubertal markers was estimated using interval-censored regression models according to sibling relatedness (full, half and/or step siblings; half and/or step siblings; no siblings; relative to full siblings). RESULTS: Girls with both full, half and/or step siblings (-1.2 (CI 95 % -2.5; 0.1) months), only half- and/or stepsiblings (-2.2 (CI 95 % -3.7; -0.7) months), and no siblings (-5.5 (CI 95 % -8.5; -2.5) months) entered puberty earlier than girls with full siblings. Boys with full, half and/or step siblings (-1.4 (CI 95 % -2.7; -0.1) months), only half and/or step siblings (-1.2 (CI 95 % -3.0; 0.6) months), and no siblings (-4.5 (CI 95 % -8.8; -0.3) months) entered puberty earlier than boys with full siblings. CONCLUSIONS: Children with sibling relatedness other than full siblings entered puberty earlier than their peers with full siblings even after adjustment for parental cohabitation status, childhood body mass index and childhood internalizing and externalizing symptoms.