Accepted for Publication: October 21, 2013.
Published Online: February 17, 2014. doi:10.1001/jamapediatrics.2013.4944.
Study concept and design: Llewellyn, Wardle.
Acquisition of data: Plomin, Wardle.
Analysis and interpretation of data: Llewellyn, Trzaskowski, van Jaarsveld.
Drafting of the manuscript: Llewellyn, Trzaskowski, Wardle.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Llewellyn, Trzaskowski, van Jaarsveld.
Obtained funding: Plomin, Wardle.
Study supervision: Plomin, Wardle.
Conflict of Interest Disclosures: None reported.
Funding/Support: Genome-wide genotyping was made possible by grant 085475/Z/08/Z from the Wellcome Trust Case Control Consortium 2 project. The Twins Early Development Study is supported by program grant G0901245 (and previously grant G0500079) from the UK Medical Research Council, with additional support by grants HD044454 and HD059215 from the US National Institutes of Health (Dr Plomin). The anthropometric data were collected as part of grant D19086 from the UK Biological and Biotechnology Research Council, with additional support by program grant funding from Cancer Research UK (Dr Wardle).
Role of the Sponsor: The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.