I have met a number of Africans that don’t know their exact age although that is getting rarer and rarer. The issue of age, in fact, shows how very different cultures can be. Although he doesn’t know his birth date he does know whether he is older or younger than everyone in his extended family and in his village. Even though his father doesn’t know his exact age both he and his father know whether his father is older than or younger than each of the father’s brothers, cousins and even neighbors. The same is true for his mother.
Almost every time an African mentions his aunts or uncles their relative age is specified, as in “my mothers older sister” or “my father’s younger brother”.
And even when none of them know what year they were born, they do know on what day of the week they each were born.
My acquaintance did not know his age, but that does not mean that his culture does not value knowing one’s age, quite the contrary. But rather it values knowing one’s age in a very different way than does my culture.
When people say that different cultures have different values, that’s true. But it is also true that many times they share very similar values but express them in wildly different ways.