We can, to some degree, modify our behaviour and appearance. But we are always limited to our history and the evolution of our body, to the concrete environment where our body evolved and developed. Natural bodies are individual and unique. Even twins do not have a completely identical body. They might have a identical set of genes but their bodies are not identical.
Bodies are physical entities.
They occupy a distinct volume in space and time. No other individual can be at the same point in space and time. Our perception of reality uses the metaphor of a geometrical three- dimensional space within which our body is located. This is also a metaphor usually used in cyberspace that you locate interactions and people, or representations of people, in three-dimensional space. This is not just by accident or by a technological bias.