These children are blood-related even though they live in different cities, as they share the same parents.

blood-related 是由 blood（血液）和 related（相关的）组成的复合形容词。blood 在这里象征"血缘关系"，related 表示"有联系的"。 blood-related 合起来表示"有血缘关系的"，指通过共同祖先或父母而存在亲属关系的情况。