You can be as old as you look, feel, speak, and think. You can also be as old as you remember geography.
I happen (a matter of accident of course) to be in my early 50’s. I remember when the USSR invaded Czechoslovakia and controlled East Germany, whose major enemy was West Germany, the capital of which was in Bonn. Of course, the Soviet fleet was based in Leningrad. Peking was the capital of Russia’s major rival, China. At the same time, there was an interesting war going down in Rhodesia, which basically produced everything internally because no one would trade with a racist regime. As for Asia, one of the poorest countries that never got into the news was Burma.
Oh, how things change, today the Russian Federation would never think of invading the Czech Republic , not the mention Slovakia, a separate entity. The Germanies have been reunited with Berlin as its capital. People take cruises to see Saint Petersburg and fly to Beijing. Myanmar gets into the news as one of the poorest and most repressive countries in the world. As for Botswana, aside from occasional government changes, who in Europe and the United States reads about it, although I have heard that it is a beautiful country and worth visiting.
On the bright side, even if your hair is grey or non-existent and your skin is no longer baby-like, if you know that going to Croatia is not a trip to Yugoslavia and the Georgia Republic is not the home of Jimmy Carter, you are still young. It could be worse: you could think the capital of Germany is Weimar! That would be a real grandfather clause.