Oh! I know a little about that: so basically it's a mix of the cultural surroundings the language develops in and the need for a way to distinguish between the objects and subjects of a sentence. If the culture a language exists in has/had at some point a concept of female nature deities for example, plants and trees are more likely to end up getting adressed as female. So even if the users of the language lose their faith in those deities or zhe knowledge of them, that may stay.

The grammar part is simply, if you have more ways to specify a noun, you can get more precise in refering to it. You can get more flexible in your sentence structure cause the things that belong to gether don't have to be close together.

I hope that makes sense.