I'm in my late 20s and still get that if I visit relatives with my parents! But Greek relatives seem to consider any unmarried children to be kids, regardless of age.

Ditto in my culture. Talking about how handsome you are (you share my genes, how can you not be handsome?) and how surprising it is that you haven't found a wife yet continues long into your 20s.

To be honest, I think this whole debate is a generalization based on a post-victorian western culture where all the frivolities concerning male appearance have died. Previously, men--at least the aristocratic sort--used to wear make up, tights, wigs and high heels all at once but now only women do.