It is quite possible that a devoted crusader of science might in childhood have pulled such a stunt—as a prank of the moment, meaning nothing in particular. But when you draw a character, everything that you say about him acquires significance by the mere fact of being included in your story. Art is selectivity. You cannot re-create every minute detail about anything, neither about an event nor about a person; therefore, that which you choose to include, or to omit, is significant—and you have to watch carefully the implications of what you say or omit. If you introduce a boy as seriously interested in medicine and then show him playing silly, childish pranks, the earnestness of his devotion is immediately undercut.