Does the setting need to bear any particular relationship to reality?
A role playing game that really has absolutely no relationship to reality, in which you cannot analogize from reality to game in any way, will not be comprehensible - characters in such a game would be "varelse".
Players need to be able to extrapolate from reality to the game in some reasonable way to figure out how to play a role in the game. So, I think it is reasonable to say that it has to bear some relationship to reality. Not a particular relationship, but there must be some for the game to be playable. You can pick and choose where you match the real world, and where you don't.
Well, in the respect that they are both PC's. Otherwise, they are two entirely different species with entirely different physical characteristics.
Well, that's just the thing, isn't it? As far as the game is concerned, if you give female humans a -2 to strength, they are nto *entirely* different. In Strength, they would then be rather similar in physical characteristics.
I don't even agree that halflings make a good comparison bench mark, so if that is what you refer to then no it doesn't make sense.
I think we may be talking past each other.
We are talking about giving female humans a -2 to strength, yes? Then any race that also has that same modifier is a benchmark for what that means, whether you like it or not, because as far as the game rules are concerned, you're making them similar.
It's like using elves as a bench mark for Constitution.
No, it is like using elves as a benchmark for what -2 Con means. If I were going to give a new race a +2 Strength, I'd look at half-orcs as a comparison, and so on.