5. Your skin becomes thinner with age
As people get older, skin can become thinner and lose some of its underlying tissue, making veins more visible—especially on the hands and arms.
6. Genetics
Some people simply inherit more prominent veins or have lighter/thinner skin through which veins are easier to see.
When should you pay attention?
A vein becoming visible isn’t usually a problem by itself.
However, if a vein suddenly becomes prominent along with pain, swelling, redness, warmth, tenderness, or a significant change in one limb, it’s worth seeking medical advice promptly.
So if you’ve noticed veins showing through your skin, don’t immediately assume it’s a warning sign.
Sometimes, visible veins simply mean your veins are close to the surface.
Your body isn’t necessarily trying to tell you something is wrong—sometimes it’s simply showing you how it is built. 
