It is surely true that a culture's mores and environment shape its language. To take a trivial example, I wouldn't be surprised if a society that had never seen an ocean and was not in contact with any other society that had would have no word for "ocean". But how far to go with this is highly debateable.
So sure, in English my father's brother and my mother's brother are both called my "uncle". My sister's husband and my wife's brother are both called my "brother-in-law". Etc. Does this lack of special words mean that we care less about family than cultures that have different words for each? Or conversely, I suppose, that we are less stratified and see many such relationships as socially equivalent? It's an interesting speculation, but without further evidence I wouldn't leap to conclusions. After all, if I want to distinguish my father's brother from my mother's brother, I can say "my father's brother" and "my mother's brother". It's not like we're unfamiliar with the concept.
There are theories that language shapes one's thinking. Like in the classic novel "1984", there's a discussion of how a tyranical government limited people's thinking by controlling the language, for example, defining the word "free" to mean only the absence of something, as in "this lawn is free of weeds", so that the idea of political freedom would be "unthinkable". An interesting idea, but would it actually work that way? After all, people throughout history have invented words to express a new idea. Like, when Demosthenes came up with the idea of an atom, that was apparently a new idea that no one had ever thought of before, so there where no words for it in the language. So he invented one, "atom". (If it wasn't Demosthenes who invented the word, feel free to correct me.) Did the lack of an existing word for the idea make it more difficult to think of the concept? Obviously it didn't stop him. Maybe it meant that it took a particularly creative person to think of it, that other geniuses were blocked by lack of a word. Such a thing is very hard to prove one way or the other. Especially given that it's easily proveable that it's not an absolute, we're left trying to prove whether it has any effect, and if so, how much.
** Further thought 6 years later **
I just got an upvote on this which brought this post back to my attention, and re-reading it I had an additional thought.
How do we name things? In this context I mean, when there are several similar things in the world, do we give each one a distinct name, or do we have a general word for the category as a whole and then use adjectives to specify which we mean.
For example, in English we have many words for different types of motor vehicle: car, truck, motorcycle, etc. People rarely say "motor vehicle", it's one of those words people resort to when they're struggling to find a general word for the category. More often we say "cars and trucks".
On the other hand, we have the general term "telephone", and when you want to be more specific you have to say "cell phone" or "wall phone" (or occasionally some other specialized kind of phone, "satellite phone" or whatever).
Using a general term with adjectives is more flexible. It makes it easy to extend the class and for people to recognize that you're talking about a member of the class even if they don't recognize the specific example. Like if you told me you had a "fwacbar phone", I wouldn't know exactly what that is but I'd at least instantly understand that it was some kind of phone.
Having specific words for each example can make language more concise. If we had to give a long description every time we wanted to refer to something, that could get very cumbersome. Like in the family member example, "my father's brother" isn't long enough to be tedious or confusing. But if you start saying, "my father's mother's sister's son's daughter", well that's just getting impractical.
But having specific words for every instance can make a lot of words to remember, which also can be cumbersome. I suppose if you use them every day you just get used to them. But in English we have many terms for relationships that most English speakers find confusing and difficult to remember exactly what they mean. Who, exactly, is my "second cousin twice removed"? Personally I don't remember and I know many other English speakers don't either.