Well, it's not really about age. It's more about the characters' feelings and circumstances. Some manhwas might challenge the idea of age and focus on true emotions instead.
The 'Am I A Daughter' manhwa might be a story about a character's self-discovery and exploration of her identity. But it could vary depending on the specific plot and themes.
Well, it's hard to say. There are so many novels out there. If it hasn't received a lot of mainstream attention, it might not be widely known as popular. However, it could be very popular within a specific community or among certain types of readers who are into that particular genre or style.