Are large families a liability or an asset for an autocratic ruler? In this article, we show that in medieval and early modern Europe, relatives protected monarchs from challenges from their elite groups, thus reducing their risk of being deposed. Women reduced the risk of both depositions from outside and from within the family, whereas men primarily reduced the risk of outside depositions (as well as the risk of civil wars breaking out). This is demonstrated in a statistical analysis of 27 European monarchies spanning the time period 1000-1799, which enlists new data on royal offspring, siblings, and paternal uncles and aunts. These findings not only elucidate power dynamics in the medieval and early modern world of dynastic politics but also have implications for present-day authoritarian states where institutions are weak and personal relationships retain their importance. I against my brothers; I and my brothers against my cousins; I and my brothers and my cousins against the world.