4 Complete the text with one word in each gap. Then add commas for any of the non-defining relative clauses. people 3 You and your ancestors For every person on the planet, there are two are their biological parents, four grandparents and eight great-grandparents. Above is a diagram? shows one person's ancestors for four generations. The top row has 16 people shows your great- great-grandparents. It's interesting to think of all the different places they lived and the people they married. If you go back 200 years in time to the 19th century, you'll probably find as many as 128 ancestors! So a stranger you pass in the street could be your long-lost cousin! 4 6 great-great grandparents great grandparents grandparents parents Luisa