Grandparents have always been important. Today, they're even more important. In busy, two-career and single-parent families, an involved grandparent goes a long way to filling a void for children. In extreme situations, the courts have found it's often a grandparent who can reach a troubled teen when no one else can.
Some people, genetically, are born with weaker or smaller veins than others - and some people are born with larger, and more flexible vein tissues. Due to genetics, some people just have poor, weak veins. This only affects the large return veins you can see however - the veins which transport the rest of your blood are likely fine. Regardless of the vein size, blood can still be drawn. I personally have smaller and weaker veins, and can still donate, but sometimes it takes a few tries.
Slow blood flow can occur if there is a narrowing of the blood vessel. This can obstruct the flow. One common cause is atherosclerosis. There are deposition of cholesterol or lipids in the wall of the arteries which can narrow it. Other causes can be an inflammation. In the veins there can be slow flow where there is difficulty in pumping blood from legs towards the heart. If you feel any symptom, you should get an examination you need to get it checked by doctor. Any query, please feel free to ask.