dd1 was gluten free for years (she now eats a normal diet with digestive supplements).
Over that time, we obviously used to tell her 'no, not for you, it's got gluten in' or similar.
she ahs always been interested in asking what she can/can't have etc.
at tea, ds had one of those Goodies
oat bars. dd1 asked what was in it, and if it had gluten etc.
she's just wandered back up to me and said 'gluten is weeds. it has weeds in. and flour'
methinks she has understood a different type of flour
and has linked back from there to overcorrect to weeds, rather than wheat...
god knows what school thinks we feed her...