Interconnecting threads

Many moons ago, my father told me this riddle... "A person approaches you & says this: 'My father's father is my father's son...' Who IS this person?" 

 

Take gentle care, SLRSB 8)I have adapted the riddle... "A person approaches you and says this - 'My mother's mother is my mother's daughter...'  Who is THIS person..". ;)  - S8)