Demography

La descendencia final is the number of children a cohort turned out to have, and la descendencia points the opposite way from the English word it resembles. In Spanish it runs downwards, to the children and their children: morir sin descendencia, la descendencia de un rey. English « descent » runs upwards instead, back towards where somebody came from — « of Irish descent » — so the Spanish word has to become « offspring » or « descendants ». One word, two directions, and only the language decides which.