My grandpa always check my hand and say I am devil. Is it just a superstition?

My maternal grandpa always looks at my little finger and the second last finger length. He has been doing it since I was a little kid. If our little finger is below the horizontal line of the second last finger we r devil, if its same level as the line we r human and if its above the line we r god. My little finger is now below the lime so he says I am a devil. He also said until age of 5 it was above the line which means I was a god.