Funding for this research was provided by:
Koninklijke Nederlandse Akademie van Wetenschappen (PAH/6635)
Vrije Universiteit Amsterdam
National Institute of Mental Health (RC2 MH089951)
Seventh Framework Program (602768)
Received: 22 February 2017
Accepted: 4 July 2018
First Online: 20 July 2018
Compliance with ethical standards
: Hill F. Ip, Rick Jansen, Abdel Abdellaoui, Meike Bartels, Dorret I. Boomsma, and Michel G. Nivard declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: For this type of study formal consent is not required.