Note that there are no crossover points through the first, fourth and fifth segments at the Great grandparent look. That means these Great grandparent segments were passed down, intact, from one of the 2G grandparents. There is a 50% probability for either one, and I selected one of those in each case for example. Now we have two “sticky segments” from the previous generation; and one “sticky segment”, 2Ggp3, which survived three generations.