Dirk J. A. Smit, Dennis van ‘t Ent, Greig de Zubicaray and Jason L. Stein Twin Research and Human Genetics / Volume 15 / Special Issue 03 / June 2012, pp 267 272 DOI: 10.1017/thg.2012.20, Published online: 15 June 2012 Link to this article: http://journals.cambridge.org/abstract_S1832427412000205 How to cite this article: Dirk J. A. Smit, Dennis van ‘t Ent, Greig de Zubicaray and Jason L. Ste...