12 February 2026

Twins wanted for research into genetic and environmental factors

Zwei rothaarige Zwillinge (Mädchen) sitzen auf einer Wiese.
© Liubov Levytska/Adobe Stock (Download nur auf adobe.com)Für das bundesweite Zwillingsregister "Gertrud" werden Zwillinge jeden Alters gesucht, die bereit sind, an wissenschaftlichen Studien mitzuwirken.

Twins can help science understand whether our lives are more strongly influenced by genetic factors or environmental factors. Researchers, including Saarland University Professor Frank Spinath, are building a nationwide twin registry for studies exploring these questions. Spinath is looking for twins of all ages who are willing to participate in scientific studies. Twins interested in participating can register in the Gertrud portal, where they can view upcoming studies.

The following text has been machine translated from the German with no human editing.

Twins are rare: only around three per cent of babies in Germany are born as twins, and only four out of every 1,000 births are identical twins. 'They can help us answer important research questions. For example, which genetic factors play a role in the development of certain diseases. Or which environmental influences can have a positive effect on the development of children and adolescents and on our health,' explains Frank Spinath, professor of psychology at Saarland University. Twins are particularly valuable for research because identical twins share 100 per cent of their genes, while fraternal twins are about 50 per cent similar.

'Since fraternal twins grow up in similar social environments even more than normal siblings, they also help the various research groups to better understand the contribution of genetics and environment to different characteristics and behaviours,' says Frank Spinath. The research projects focus, for example, on lifestyle, nutrition and sport, but also on special life events or social circumstances that shape everyday life and interpersonal relationships.

Twins aged 16 and above can register themselves in the nationwide 'Gertrud' registry using an online form, while parents can register younger twins on their behalf. They will be contacted by email when new studies are available and can then give their consent if they wish to participate in the respective study. The 'Gertrud' registry, short for 'German Twin Registry', is located at the Max Planck Institute for Human Development and is coordinated from there in collaboration with several universities and research institutes that have been active in twin research for many years. These include the Max Planck Institute for Empirical Aesthetics, Bielefeld University, Saarland University, Medical School Hamburg and Tübingen University Hospital.

'We hope that word will spread here in the region that twins can make an important contribution to international research. So if you know any twins in your family or circle of friends, please let them know about the new nationwide registry. Age and place of residence are secondary for us; the only important thing is a willingness to contribute some time and openness to scientific questions,' says psychology professor Frank Spinath.

Further information

Information about the nationwide register, twin research and current studies: www.gertrud.info

Questions answered by:

Prof. Dr. Frank M. Spinath
Saarland University
T: +49-681-302-64079 
Email: f.spinath(at)mx.uni-saarland.de

Porträtfoto am Schreibtisch
© Thorsten Mohr/UdSFrank Spinath, Zwillingsforscher an der Universität des Saarlandes, beschäftigt sich seit vielen Jahren mit der Frage, ob unser Leben stärker von genetischen Einflüssen oder von Umweltfaktoren geprägt ist.