Research has demonstrated that couples have similar partisan preferences, a finding associated with political polarization. However, it remains debated to what extent different mechanisms contribute to this homogamy. Analyzing dyadic panel data from the German Socio-Economic Panel 1984–2020, we distinguish analytically between (1) direct political matching (i.e., partner selection on matching party preferences); (2) indirect political matching (i.e., social structural homogamy with political homogamy as a by-product); and (3) couples’ political alignment over time, to explain party preference similarity. First, we study matching among recently formed couples using an innovative method that compares real-world couples with three types of counterfactuals: couples that are matched (1) randomly, (2) by multidimensional social structural characteristics, and (3) by maximizing similarity in party preference. Second, we study couples’ political alignment over the course of relationships, tracking real-world couples over time and controlling for macro-level changes in the party-political landscape. Results indicate substantial political homogamy among recently formed couples, which is best explained by political matching (i.e., direct selection based on partisan preferences). Effects of social structural homogamy appear weak in comparison and rather stable across cohorts. Couples further align in their partisan preferences over time, but this effect is countered by an increasing heterogeneity of the German political landscape.

中文翻译：

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为什么合作伙伴往往更喜欢相同的政党？来自德国夫妇的证据


研究表明，夫妻有相似的党派偏好，这一发现与政治两极分化有关。然而，不同的机制在多大程度上促成了这种同质性仍然存在争议。通过分析德国社会经济小组 1984-2020 年的二元小组数据，我们在分析上区分了（1）直接政治匹配（即根据匹配政党偏好选择合作伙伴）； （2）间接政治匹配（即社会结构同偶性和政治同偶性作为副产品）； (3) 夫妻随时间的政治倾向，以解释政党偏好的相似性。首先，我们使用一种创新方法研究最近形成的情侣之间的匹配，该方法将现实世界的情侣与三种类型的反事实进行比较：（1）随机匹配的情侣，（2）通过多维社会结构特征匹配的情侣，以及（3）通过最大化相似性匹配的情侣在政党偏好中。其次，我们研究夫妻在关系过程中的政治立场，跟踪现实世界中夫妻随时间的变化，并控制政党政治格局的宏观变化。结果表明，最近结成的夫妇之间存在大量的政治同婚现象，这最好的解释是政治匹配（即基于党派偏好的直接选择）。相比之下，社会结构同质性的影响显得较弱，并且在不同群体中相当稳定。随着时间的推移，夫妻的党派偏好进一步趋于一致，但这种影响被德国政治格局日益异质性所抵消。