Objective This study examines the prospective and bidirectional association between personal identity processes and relationship formation using longitudinal survey data from Finland.Background Although psychological factors have increasingly been studied as determinants for family formation processes, the role of identity exploration and commitment processes for relationship formation has been underexplored. We show that identity (un)certainty in the domain of future life plans is an important driver for relationship formation, and that relationship status may shape identity (un)certainty in turn.Method We apply event-history analyses in order to study the prospective power of both separate identity processes (variable-centered approach) and clusters of these (person-oriented approach) on relationship formation risks. Furthermore, we conduct fixed effects linear regression models for examining identity development over time based on relationship status.Results Findings suggest that identity uncertainty is negatively, and certainty is positively associated with relationship formation risks over time. Results based on cluster analyses support these findings, that is, committers are more likely to enter a relationship, in particular marriage, than explorers. Mixed findings with regard to identity development over time emerge. Whereas firm identity (i.e., commitment) remains stable over time among partnered individuals, it decreases among singles. However, relationship status does not impact exploration developments.Conclusion Relationship formation decisions in contemporary Finland are intertwined with the (un)certainty of personal identity.

Having leadership skills (LS) may increase an individual’s chances of ascending to a higher rank in hierarchical social structures, which can, in turn, provide the resources needed to support a partner and/or a child. Nevertheless, research on the association between LS and family formation processes (marriage, fertility) is scarce. We explore the prospective association between LS and marriage/completed fertility for 650941 Swedish males. Poisson regression and linear probability models are applied, including sibling fixed effects models. Our findings demonstrate a positive association between men’s LS, as measured at the age of assignment to military service (17–20 years), and their probability of marrying by age 39 or older (depending on the birth cohort). Furthermore, among the men in our sample, we find that LS are positively linked with the number of children, and are negatively linked with the probability of remaining childless. These associations are only partially explained by education and income.

Personality has increasingly become relevant for family formation processes. However, the association between personality and family formation (dissolution) has been underexplored in demographic research. This study contributes to existing research by examining the prospective association between two personality factors [social maturity (SM), and emotional stability (ES)] and family formation and dissolution processes, i.e., (1) marital status, (2) fertility, and (3) partnership dissolution as both (a) divorce and (b) cohabitation dissolution, based on large Swedish register data. Poisson regression, Linear Probability, and Cox proportional hazard models were applied for different outcomes. Findings suggest that males with high scores on SM and ES measured at age of assignment to military service (17–20 years) are more likely to get married by age 39 and above. Regarding fertility, SM and ES show positive associations with offspring counts and negative associations with the probability of remaining childless by age 39 and above. Relationship dissolution is negatively linked with SM and ES, in particular among the lowest personality scores. Further analyses using sibling comparisons support these findings.

Amid rising concerns about climate change, in recent years, demographers have increasingly examined whether environmental concerns have become a factor in shaping reproductive intentions and outcomes. However, little is still known about the potentially reciprocal relationship between environmental concerns and fertility, in part due to the lack of longitudinal analyses of sufficient temporal scope. Our study provides new results based on unique data from the German Socio-Economic Panel (GSOEP), which contains both full fertility histories and yearly (1984 to 2020) measurements of environmental concern. We follow individuals born between 1965 and 2000 and investigate (a) whether environmental concerns predict first-birth quantum and timing and (b) whether environmental concern trajectories vary between eventual parents and the childless. Overall, results indicate no significant link between environmental concerns—whether early in life or across the life course—and (the timing of) the transition to parenthood, or the number of children achieved by age 40. However, we find a negative association between environmental concerns and the chances of becoming a parent for older birth cohorts, suggesting a potential generational shift in how ecological awareness intersects with fertility decisions. Moreover, parents seem to be more worried about the environment than the childless, though these differences seem to be largely explained by unobserved heterogeneity rather than parenthood itself.

The role of psychological factors for family formation processes has been underexplored in demographic research. However, psychological concepts such as personality, identity, or skills may have become increasingly relevant for family formation processes such as marital behavior, childbearing, or partnership dissolution, in particular in countries with high levels of individualism. This dissertation aims to address this research gap in various ways. First, the dissertation chapters examine the prospective associations between personality and family formation (marriage, fertility, dissolution) (chapters 1 and 2), identity and marriage (chapter 3), and leadership skills and family formation (marriage, fertility) (chapter 4). Second, the potential mediating role of socio-economic status indicators (income, education) for these relationships is explored (chapters 2, 3 and 4). Third, full siblings are compared to each other when applicable in order to control for shared background factors such as genetics or parental background (chapters 2 and 4). For these purposes, different data sources are used including large and representative survey data from Germany (chapter 1), Swedish register data (chapters 2 and 4), and survey data from Finland (chapter 3). Methodologically, a mix of widely used analytical methods have been applied such as event-history analyses, linear probability models, or Poisson regression models including individual and sibling fixed effects. The findings of this thesis suggest that psychological factors shape family formation processes across the selected European countries (Germany, Sweden, Finland) with high levels of individualism. Personality factors linked to social abilities (extraversion, social maturity, agreeableness) generally show positive associations with childbearing (chapters 1 and 2) and the probability to get married, and negative correlations with dissolution processes (chapter 2). Emotional stability is also positively associated with family formation processes (marriage, fertility), and negatively linked with partnership dissolution (chapter 2). However, these associations only relate to patterns for males whereas females do either not show clear associations (chapter 1), or had to be neglected based on data restrictions (chapter 2). Furthermore, certainty and commitment with future life plans (as indicator for identity) are positively linked with marriage risks over time (chapter 3). Regarding leadership skills (LS), as one specific type of skills, similar associations to personality effects from study 1 and 2 have been found, i.e. LS are positively correlated with marriage and fertility (chapter 4). The mediating effects of income and education, are relatively small for all associations so that future research may examine the role of other potential mechanisms such as intentions, attitudes, or health. Additionally, sibling fixed effects approaches do not show large difference compared to the patterns that are described above.