196
closeness and, therefore, informs the likelihood of developing significant
relationships over the life course (Doherty and Feeney 2004 ). During
childhood, individuals’ relationships are first developed in their family
with their parents, siblings, and potentially with other members playing
a key role (for instance grandparents or even godparents). School pro-
vides opportunities to go beyond the family circle and develop friend-
ships, which are still mediated by the family. While parents tend to
occupy a key position in their children’s networks over the life course
because of intergenerational solidarity (Bonvalet and Ogg 2007 ), siblings
tend to be in second or third position and regain importance in case of
need or in old age (Cicirelli 1995 ; White 2001 ). Higher education (sec-
ondary and tertiary) provides room for friendship and extensive sociabil-
ity. After this preparation period, in Kohli’s tripartition model (Kohli
2007 ) the period of employment is less favourable for sociability, espe-
cially when individuals also experience partnering and parenthood
(Bidart and Lavenu 2005 ; Degenne and Lebeaux 2005 ). Partners tend to
create a joint network over time (Kalmijn 2003 ) and to focus more on
their household members when they become parents. However, this does
not follow a ballistic model, as critical life events may occur throughout
the life course, such as divorce, triggering the loss of relationships and/or
the activation of old or new relationships (Kalmijn and Broese van
Groenou 2005 ; Terhell et al. 2007 ).
This chapter proposes a significant theoretical and methodological
development of a technically comparable analysis presented in a previous
publication focusing on the transition to adulthood of a cohort of indi-
viduals born in the 1970s (Aeby et al. 2017 ). First, it uses a sample twice
the size, thereby ensuring more robust results. Second, it considers not
one, but two birth cohorts (1970–1975 and 1950–1955), thus broaden-
ing the scope of analysis from the transition to adulthood to the entire
period of adulthood. Third, the typology of life trajectories presented in
this chapter is different, as it is no longer based on the age of individuals,
but on historical time (from 1990 to 2010). In this respect, it offers a new,
original perspective on adulthood as a process shaping personal relation-
ships. Fourth, the theoretical framework of the chapter has been accord-
ingly and thoroughly developed, by addressing the linkages between social
context (at macro and micro levels) and life transitions in more detail.
J.-A. Gauthier et al.