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  • Title: TwinLife - A genetically informative, longitudinal study about the development of social
  • Principle Investigators: Prof. Dr. Martin Diewald (martin.diewald@uni-bielefeld.de);
    Prof. Dr. Rainer Riemann (rainer.riemann@uni-bielefeld.de);
    Prof. Dr. Frank M. Spinath (f.spinath@mx.uni- saarland.de)
  • URL: http://www.twin-life.de/

Study info

TwinLife is a 12-year representative behavior genetic study investigating the emergence and development of social inequalities over the life course. The long-term project began in 2014 and surveys more than 4,000 pairs of twins and their families in different stages of life on a yearly basis. All of the subjects reside in Germany. Not only social, but also genetic mechanisms as well as covariations and interactions between these two factors can be examined with the help of identical and fraternal same-sex twins. In order to document the individual development of different aspects it is important to examine the families extensively over the course of several years. Six important contextual domains are focused on: 1.) Education and academic performance / skill development, 2.) career and labor market attainment, 3.) integration and participation in social, cultural and political life, 4.) quality of life and perceived capabilities, 5.) physical and psychological health and 6.) behavioral problems and deviant behavior. In order to take a close look at the development of social inequalities, TwinLife does not only examine different etiological factors, but also different indicators of personal and social success and failure respectively. On part of the conditional factors genetic disposition as well as aspects of the environment that the children and adolescents are living in are considered. On part of the consequences not only objective but also subjective information is observed. Children are born into an environment which influences them, but on the other hand they react and interact differently depending on their individual characteristics and thereby shape their environment. To allow for an accurate examination of the reciprocal processes by which individual dispositions and environmental conditions influence each other, data on the illustrated characteristics will be collected over a period of twelve years.

In the following, the TwinLife Data are described in more detail by the life domains outlined above: 1.) Education and academic performance / skill development: In this domain data on grades, educational motivations, levels of education are collected in addition to information on cognitive abilities, personality traits / noncognitive skills and their development. 2.) Career and labor market attainment: This domain includes information on the current occupation, the current occupational position and the income (or, if applicable, on the receipt of social benefits) as well as on the perceived job security, job satisfaction and the commitment to work. 3.) Integration and taking part in social and political life: Here, characteristics of the social environment of the persons such as the support through the family, friends and spouses are included. Furthermore, data on social and political commitment as well as social resources are collected. 4.) Quality of life and subjectively perceived quality of life: This domains contains information on person’s self-esteem as well as on global and domain specific life satisfaction. 5.) Physical and psychological health: Here, assessments of general health, on specific diseases, but also on subjectively perceived impairments, on medical check ups (health record books) as well as on health behaviors are covered by the data. 6.) Behavioral issues and deviant behavior: Information on criminal behavior as well as on the degree of internalized and externalized problematic behavior is surveyed in this domain. In addition, information on environmental characteristics such as the socio-economic status (SES) of the families, the family structure, the relations among the family members as well as characteristics of the neighborhood are contained in the data.

The data release consists of four files. Two of them contain similar information in two different formats. One of the two is a SUF-data file in person format (i.e., in a format with one data row per person) and the other is a SUF-data file in family format (i.e., in a format with one data row per family). In addition, a data file with the information of the survey for the zygosity assessment of the twin pairs and a data file documenting the survey mode for each variable on the person level is part of the data release.

Note: Part of the data was collected using a paper&pancil-questionnaire (documented as "3: P&P self-administered questionnaire" in the survey mode dataset). Some persons using this survey mode answered some questions they should not have answered according to the conditioning rules of the questionnaire. In a few cases person filled in a paper&pencil-questionnaire which should not have done so according to the participation rules of the survey. Both cases of additional responses are contained in the datasets delievered to the data users. Please be aware of this peculiarity in preparing and analyzing the data.


The TwinLife panel combines a sequential cohort-design with an extended twin family-design (ETFD). The related surveys are conducted yearly, whereat the mode alternates between face-to-face at home, including some tests, and telephone interviews. Parts of the face-to-face surveys are conducted in parallel modes, i.e., as computer assisted or paper-and-pencil self-interviews.

The sequential cohort-design comprises four cohorts: The youngest twins in cohort 1 (birth years 2009 and 2010) are about 5 years of age at the time of the first survey in 2014 and 2015. The oldest twins in cohort 4 (birth years 1990 to 1993) are about 31 to 32 years of age at the time of the last survey in 2022 and 2023. The twins in cohorts 2 and 3 are born in the years 2003 to 2004 and 1997 to 1998, respectively. This design enables the TwinLife panel to cover an age range between 5 and 32 years with a data collection phase of 10 years. This age range covers important life-course transitions from school entry to the labor market entry phase as well as critical life stages for mating and family formation.

As part of the ETFD, in addition to the twins themselves the biological and if applicable social parents as well as the sibling that is closest in age to the twins are surveyed. Moreover, the partners of adult twins are included as well. This family perspective enables comparisons regarding different degrees of genetic similarity, and it is important to analyze the manifold influences of the family environment on the development of the twins in greater detail.

Geographic Coverage: Germany

Universe: Twins and their families (Extended Twin Family Design, ETFD): Monozygotic and dizygotic same-sex twin pairs born in the following years: 1.) 1990 and 1991, 2.) 1997, 3.) 2003 and 4.) 2009 (4 birth cohorts) + at least one biological parent (+ if possible the other biological parent, step-parent(-s), one sibling and the twins' partners)

Selection Method: Twin families are drawn from local resident registers in communities with at least 5,000 inhabitants in Germany. The twin families are recognized as such if two same-sex people with the same date of birth lived in the same household. Then, it was checked whether the selected persons were twins indeed.

Mode of Data Collection: Household interviews with the family via three different interview modes (CAPI, CASI, Paper-and-Pencil) plus cognitive tests, scans/photos of certificates and children's health record books; interviews with family members living outside the interviewed households by two modes (CAWI, Paper-and-pencil).

Data Collector: First wave (first Face-to-Face interview): TNS Infratest

Date of Collection: 10/01/2014 to 05/31/2015 (Face-to-Face 1a)

Data access

GESIS Data Catalogue: https://dbk.gesis.org/dbksearch/index.asp

Data description

Study units

Number of Units: F2F 1a: 10510 individuals, 2009 families

Number of Variables: F2F 1a: 2568 (individual format), 8895 (family format)

Other material and Notes

Availability Class: C (Data and documents are only released for academic research and teaching after the data depositor’s written authorization. For this purpose the Data Archive obtains a written permission with specification of the user and the analysis intention.)

Further Remarks: TwinLife website: http://www.twin-life.de/en

Study info

Name: twinlife

Label: TwinLife


Name Label Conceptual Period Analysis unit
za6701_person_v1-0-0 Person-year survey dataset gross/net/gen long person
za6701_zygosity_v1-0-0 Zygosity dataset net/gen wave 1 F2F person/family


Name Label Period Analysis Unit
twinlife-2014-f2f_modul1_zygk1k2 Module 1: Zygosity questionnaire for cohorts 1 and 2
twinlife-2014-f2f_modul7_euek Module 7: Parents on children
twinlife-2014-f2f_modul1_zygk3k4 Module 1: Zygosity questionnaire for cohorts 3 and 4
twinlife-2014-f2f_modul5_casi Module 5 CASI questionnaire: Less sensitive information
twinlife-2014-f2f_modul3_basismodul Module 3: Basic module
twinlife-2014-f2f_familienprotokoll Family protocol
twinlife-2014-f2f_modul6_betreuung Module 6: Child care
twinlife-2014-f2f_haushaltsfragebogen Household questionnaire
twinlife-2014-f2f_modul5_dropoff Module 5 paper questionnaire: Less sensitive information
twinlife-2014-f2f_alteri-fragebogen Paper questionnaire for Alteri
twinlife-2014-f2f_modul4_casi Module 4: Sensitive personal information
twinlife-2014-f2f_modul9_zeugnis Module 9: Certificate questionnaire
twinlife-2014-f2f_modul9_zeugnisfoto Module 9: Certificates
twinlife-2014-f2f_alteri-onlinefragebogen Online questionnaire for Alteri
twinlife-2014-f2f_modul8_uheft Module 8: Health record book

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