mct16:
Balthazar:
too young for a consensual sexual relationship with Haddock
mtc16:
But not too young to go around the world chasing gangsters and spies, getting appointed to a senior military position ("Broken Ear") and going to the moon.
No indeed! I think this is precisely the enigmatic magic of Tintin for child readers. He's completely unrestricted by any of the normal limitations of being a real child, ie: having to attend school, not being able/allowed to drive, fly, travel independently, use firearms, sign up for exciting professions, etc; yet because he's notionally a boy, he's simultaneously completely unencumbered by any of the aspects of normal adulthood that have little appeal to most child readers, such as worrying about money, having a love-life, having responsibilities to dependants, etc.
As has been discussed on other threads about Tintin's age, Hergé himself once said that he regarded Tintin as ageing between about 14 and 19 over the course of the books. Clearly some readers (particularly modern readers) view him as considerably older than that. Yet at the same time, his apparent lack of sexuality can make him seem pre-pubescent. He's just not a realistic child/teen or a realistic adult either.
I think the reason for this is that Hergé didn't create his characters as realistic, logical people with well-rounded back-stories. They tend to be archetypal characters more in line with clowning or silent movie characters than with literary novel characters - characters who stem from a visually pleasing idea, rather than necessarily adhering to the rules of literary naturalism. This style of character creation seems quite normal within the context of Hergé's early cartoony black-and-white books. As the books become more sophisticated and everything else in the books becomes more realistic, perhaps the lead characters' lack of sociological realism becomes more noticable by contrast and (for some readers) more odd.
In their first appearance in the b/w version of Cigars of the Pharaoh, the Thom(p)sons are simply caricatures of police agents, X-33 and X-33A, and a reader probably doesn't think about them having a life or a history outside the frames of the comic strip or wonder about their genetic or sexual relationship. By the time we get to the middle and later books, everything else about the Thom(p)sons' appearance and character has become so realistic and well-rounded, and everything about the world around them has become so realistic and well-rounded too, that we start to wonder about their relationship and identity the way we would if we met them in real life.
The fact that the books give us no answers and no back-stories is a good thing, of course!