Many languages have terms for siblings that define whether one is younger or older in relation to another sibling.
Navajo translates accordingly but for a different reason: “since Martha seemed to take the responsibility of the housework, she was probably the older of the two.” (Source: Wallis 2000, p. 103f.)
In Fuyug Lazarus is assumed to be the oldest sibling on the grounds that he died first. (Source: David Clark)