Thanks NYAhmadi and Sabah. What you both said definitely makes sense. And obviously, there is are no right or wrong answers to these questions.
I always think that any such phenomena can best be explained or explored using the principles of regression. I.e., not single, but numerous factors or driving forces result in a certain output. Culture is definitely one of them. Whether it's people's social behavior, beliefs, or interests, all act parallel to result in one output.
Similar to these driving forces, there are also numerous angles of observation to explore culture. Both of you looked at the same thing with a different perspective.
My personal understanding and definition of culture has changed many times over the years. It's an exploration that does not have an end, as there is not one definitive answer. Among all the answers that anthropologists have put out there, different people choose the one that appeals to them. It pretty much comes to a matter of choice or personal sensibility like a belief in a concept.
So if I were to define culture in this given point of time in my life, I would say it's the reflection of human conscious or thought at a collective level. It's is true that this definition is not very clear in itself, and actually is quite debatable since human conscious itself is based on different physical, biological, and social factors like NYAhmadi mentioned. So why pick something to delineate culture if that 'something' itself can be delineated by 'something else'? After all, logically speaking, if B results in C and A results in B then A results in C.
Well, I think there are times when we need to come to a 'pivot', which acts on behalf of other things to drive something bigger. It's just more productive, efficient, and convenient to do so. I am not contradicting any definitions or other factors that derive and change a culture, I am simply trying to reach something pivotal (which itself may be a result of other forces).
Now, it could also be said that why human conscious or thought should be chosen as a pivot? Why not some other factor or forces, say, social behavior to explain culture? The reason, in my opinion, is that a pivot must be something that has the characteristics of optimal number of factors that act as the rotating force behind it. For example, if we take NYAhmadi's account on nature and theoretical contradiction as two big factors, we can argue that human conscious possess characteristics of both of these factors. Whether it's our physical environment, biological needs, cognitive abilities (Sabah's point on Arts), or supernatural beliefs, all develop one common thing and that is human conscious. This conscious further derives every major or minor thing that is part of a culture.
Any biological/physical or cognitive need results in development of our conscious and this development further is reflected in the culture. Every time human conscious transforms into something different at collective level, it effects and changes the culture.