Information for Families

We have compiled the most important information about the Twin Registry, including the reasons for participating, the benefits of your participation, and an overview of our data protection measures, in the About GERTRUD section for you and your children.

You can find instructions on the best way to register your children on the registration page.
Please note: The registration form is currently only available in German. 

Should you have any further questions, please do not hesitate to contact us at gertrud@mpib-berlin.mpg.de.

 

Twin Pregnancies

Only approximately 1.8% of all pregnancies in Germany are twin pregnancies, with identical twins accounting for up to 30% of these cases. Since twin pregnancies are classified as high-risk pregnancies, close monitoring of the expectant mothers is recommended.

In the following interview, Dr. Annette Isbruch, Senior Physician at the Helios Klinikum in Berlin-Buch, answers many important questions regarding twin and multiple pregnancies: https://www.helios-gesundheit.de/magazin/schwangerschaft/news/mehrlingsschwangerschaft/ 

 

Useful information for families expecting multiples

The Federal Ministry for Family Affairs, Senior Citizens, Women and Youth provides a portal with information on legal regulations and support services for families expecting multiples: https://familienportal.de/familienportal/lebenslagen/schwangerschaft-geburt/zwillinge-mehrlinge 

 

Twin Literature Tips

German

• Bryan, E. (1994). Zwillinge, Drillinge und noch mehr ...: praktische Hilfen für den Alltag. Huber.
• Lersch, P., & Haugwitz, D. von. (2012). Leben mit Zwillingen!: Gut durch Trotzalter, Kindergarten und Grundschule. Georg Thieme Verlag.
• Haberkorn, R. (1996). Zwillinge: Wissenswertes für Zwillinge, ihre Familien, Freunde und Pädagogen. Rowohlt.
• Spektrum der Wissenschaft Highlights (2016). Gene und Umwelt - Wie wir werden, was wir sind. Springer.
• Neyer, F. J. & Spinath, F. M. (2008). Anlage und Umwelt: Neue Perspektiven der Verhaltensgenetik und Evolutionspsychologie. De Gruyter Oldenbourg.

 

English

• Segal, N. L. (1999). Entwined lives: Twins and what they tell us about human behavior. Dutton/Penguin Books.
• Leonard, L. G. & Denton, J. (2006). Preparation for parenting multiple birth children. Early Human Development, 82, 371–378.  doi:10.1016/j.earlhumdev.2006.03.009
• Plomin, R. (2018). Blueprint: How DNA Makes Us Who We Are. Allen Lane.
• Knopik, V. S., Neiderhiser, J. M., DeFries, J. C. & Plomin, R. (2016). Behavioural Genetics. Worth.

 

Similarity of Twin Pairs at Birth

Identical twins develop from the same fertilized egg and are therefore genetically identical. They are typically also very similar in their physical and mental characteristics; nevertheless, they exhibit differences that are visible and measurable shortly after birth, and, in some cases, even prenatally. This may be attributed, in part, to specific features of the prenatal developmental environment experienced by twins.

A distinction is made, for instance, between monochorionic and dichorionic twins. Monochorionic twins share a single placenta (chorion) but usually each have their own amniotic sac (amnion). Monochorionic twins are almost always identical (monozygotic) twins. In these cases, the fertilized egg divides between the 4th and 7th day after fertilization. If the division occurs earlier, dichorionic identical (monozygotic) twins develop, meaning that each embryo forms its own placenta. In contrast, fraternal (dizygotic) twins are always dichorionic because they develop from two separate fertilized eggs.

In the case of monochorionic twins, an unequal supply of nutrients and oxygen may occur, which can lead, among other things, to differences in size and weight. Furthermore, the placenta serves as the primary interface for the exchange of signals between mother and child. Consequently, factors within the prenatal environment may exert differing influences on the twin fetuses, depending on whether they share a placenta or not.

The fact that the prenatal environment is not identical even for identical twins is evidenced, for example, by the fact that their fingerprints and brain structures differ. Fingerprints develop during early pregnancy and are strongly influenced by random factors, such as position within the womb and the manner in which the fingers touch the amniotic sac. Although studies have shown that monozygotic twins exhibit greater similarities in most regions of the brain than dizygotic twins, differences are nonetheless present shortly after birth. How these differences arise remains a subject of ongoing research.