It is said that everyone has "a twin" somewhere; and given the fact that all faces have only brows, eyes, noses, mouths, and chins with various bone structures, there is bound to be someone who looks very similar to another person somewhere in the world. But can that person be so close that you mistake his offspring for yours, and his offspring think you're him?  Apparently so!
WBRC FOX6 News - Birmingham, AL

According to Fox 6, Joseph Fuller went to Edisto Primary School in Columbia, SC to pick up his grandson.  He walked up to the young man, hugged him, asked if he was ready to go (the young man responded that he was), and they left together.  It wasn't until minutes later that it was discovered that the boy in the car was not the man's grandson.  The grandmother was in the car when the boy was picked up but never looked up at him.

Oddly, the student is said to have thought the man was his grandfather as well.

The man returned the student to the school, which says it will review checkout policies as well as install new entrance ways to limit access to the school.