All of that, without a particular order and in various proportions, adds to what the cultural background of each of us is made of... so in my view, as long as someone is not me - we can talk about cultural differences, just the extent of those will vary. If I were to arrive at my own definition of what one's culture is, it would be:

Set of unique, dynamically changing contact lenses through which each person views and interprets the world. As we go through life, the contact lenses naturally adapt but we can also replace one set for another set of lenses intentionally. Taking the contact lenses completely out could be equal to erasing someone's memory.