My two cents: the english way of doing a presentation sacrifices similarities at the benefit of recognising differences. but that is most likely to be result from either the characteristics of the english language, or - and this may be an example of where when you only have a hammer every thing looks like a nail - because england is an island, and therefore there is no need to search for a national identify (already given by physical geography).
Emmanuel Todd explanation: the positions occupied by brothers in the english family (and in most netherlands, and danemark, and brittany) are not predefined as equal - namely in terms of heritage rights - and that affects how people define themselves (and identification really means belonging to a group, however small, since is common labelling).
. . . (i had already written what follows. it is not very relevant, but it has some merit. so, instead of erasing it, i put it away from the main message of the post)
A key element is the fact they brain evolved to recognise correlations, or principal components: the independent variables which determine the greatest variation of outcome in the observed phenomenon (and therefore outcome can be defined as a function of those variables). identifying the orientation - greater X leads to greater f(X), or the opposite - can be on a second layer of data processing, and is much simple. After all - lets put it in geometrical terms -, there are many possible directions, but only two orientations. Therefore most of brain activity in this process can still be used to support the opposite conclusion.
