system
Given the following post, respond as if you're commenting on Reddit:
human
Why are our veins asymmetrical?

I would think that since most things in our bodies are symmetrical, that our venous channels would be as well. I was looking at my arms today and found it strange that my veins are quite different in each forearm. Does this have something to do with development, or are veins just formed randomly? Do our veins change location throughout our lives (like rivers) depending on where they are needed?
gpt
Veins aren't exactly formed randomly, but there are random elements in how they are formed. Identical twins will have different vasculature, for example.

This is because the body doesn't have a blueprint in the traditional sense, it is procedurally generated. Limb buds set up gradients of hormones that tell bones where to stop and start.

Many blood vessels are set in stone, like the aorta and vena cava, but farther out the vessels are procedurally generated, so left and right end up similar but different.

Veins do not move based on need.