This article investigates the impact of party membership on MPs’ morality policy voting behaviour, going beyond the common dichotomy of left and right parties and differentiating the preferences of other party families (e.g. Christian democrats, Liberals and Greens) regarding abortion, stem-cell research and euthanasia. We argue that parties generally face a ‘self-determination vs. protection of life’ trade-off. In the case of embryo research, however, a party’s economic preferences and its position towards the freedom of research come into play, too. Exploring eight free votes in Germany after 1990, our analysis identifies party membership as the key determinant, supporting the claim that parties are groups of people who share common values. Moreover, we corroborate our subfield-specific argument, as regarding stem-cell research, Christian democrats vote less conservative and the liberal position of Greens even reverses.