197Research Aim
Our main aim is to understand how the personal networks of adult indi-
viduals are shaped by their past co-residence trajectories, as a proxy of
individuals’ biographies, in the frame of different contexts, structural lev-
els, and conditions. This main research issue can be divided into two
specific research questions.
- As the adult life course is said to have become more individualized and
 pluralized, our first goal is to map the diversity of co-residence trajec-
 tories in the past 20 years and to compare the main types of trajecto-
 ries across countries. Diversity in co-residence trajectories will be
 logically associated, but not exclusively, with the age and the birth
 cohort of individuals, as the former indicator reflects the position in
 the life course of the respondents and the latter takes into account
 their location in time. Indeed, as a reminder, the window of observa-
 tion covers the age spans of age 15–35 (for individuals belonging to
 the 1970–1975 birth cohort) and age 35–55 (for individuals belong-
 ing to the 1950–1955 birth cohort). It will also depend on the timing
 of leaving the parental home, the presence or absence of a stage of
 living alone, the timing of becoming a parent, and the presence or
 absence of union dissolution. Other exo- as well as endogenous factors
 may additionally influence this sensitivity, such as fluctuations of the
 economic and or political situation in the considered welfare states.
- To understand the linkages between family trajectories and personal
 networks, we will investigate the impact of biographical factors (co-
 residence trajectories) on the composition of personal networks, con-
 trolling for the macro context (country) and a set of structural factors
 measured at the individual level (birth cohort, gender, and education).
 For instance, trajectories including a transition to parenthood will cre-
 ate major changes in young adults’ sociability associated with the gen-
 dered master status (Levy and Widmer 2013 ), thus encouraging a
 focus on kinship ties, mediated by a priority focus set either on domes-
 tic or on occupational activities, whereas living for a long period in a
 single-person arrangement (alone) may foster the salience of non-kin
 relationships and full-time occupation.
Linking Family Trajectories and Personal Networks