Patterns and sources of life satisfaction stability and change at different developmental stages.

How life satisfaction develops across several stages of development and to what extent genetic and environmental factors contribute to its stability and change was the focus of this multimodal study. The sample comprises 10,277 participants from the German population-based twin family panel TwinLife including twin pairs from three birth cohorts (Npairs = 2,042, aged 10-33 years), twins' full siblings, and their biological parents (aged 10-81 years). Latent state-trait change models were used to disentangle stable and time-dependent individual differences, as well as variance in systematic change of life satisfaction, measured repeatedly across 8 years. Quantitative genetic models were applied to estimate genetic and environmental contributions to these variance components. Polygenic scores were added to these models for a genotyped subsample (N = 4,581). By analyzing longitudinal twin data and polygenic scores across several developmental stages, the study contributes to the ongoing debate about differences in the heritability of well-being. Life satisfaction showed high rank-order stability (r = .47-.89), which increased with age, and a U-shaped mean-level trend from early adolescence to middle adulthood (Δ ≈ ±0.5 SD). Moreover, 17%-37% of stable life satisfaction differences were explained by genetic differences, while variance in systematic change was entirely environmental, except for young adults, where genetic variance started to emerge. Polygenic scores supported this, as they significantly predicted stable differences (R² = .015), while associations with change were weaker (R² = .002). The prediction of stable differences increased with rank-order stability throughout adolescence and young adulthood (R² = .038) but decreased with the transition to middle and older adulthood (R² = .012). (PsycInfo Database Record (c) 2026 APA, all rights reserved).