There are two separate questions in the room here, really, aren't there?
One is "are we all, fundamentally, equal?" and the answer to that, I should hope, ought to be an unequivocal "yes".
Point in case: despite having been born and bred upper MC, I come from a family where, by tradition, on Saturday family luncheon would consist of "bread and [insert topping as determined by value here]. Whereas this would boil down to "proper ham for the men and older boys and random cold cuts for the women and children". I'd argue that this is fundamentally wrong. To the extent that, being an executive in my thirties these days, I've still got an irrational desire to be a "ham person" despite a salary that would easily allow me to procure the whole bloody pig once a week.
The other question is "ought children to accept that they do not necessarily take precedence - within the family as well as in general?". And, again, for me this is a clear "yes".
I realise I'm not being very useful in terms of the "who gets the desired seat" situation here. But my point, perhaps, is this: it's a question of motivation. Are you trying to model some kind of meritocracy, in which case an adult should argiably get the top spot on the grounds of actual contribution or are you approximating the monarchy where it is, more or less, an accident of birth?
Personally, I think it matters!