Having Gray poop is usually caused by drainage problems with your biliary system and it's not normal at all.
Your biliary system is consists of your gallbladder, pancreas and liver.
If your stools are gray in color it means that your poop lacks the proper bile which makes your poop brown like it should be.
You should go see a doctor if your poop is gray in color and not brown since having gray poop means something is wrong and it's not normal to have gray poop.