What does Marcellus notice that Cameron and Tova have in common?

Marcellus comments that he has honed his observations of humans over the 1,329 days of his captivity. He has noticed traits that humans have alike who are related to one another. Most humans who are related walk alike, and Cameron and Tova have the same gait. They also have heart-shaped dimples on each of their left cheeks. Both of them have greenish-golden flecks in each of their eyes, and they both have a toneless manner of humming when they mop. Marcellus says that Cameron is a direct descendant of the Tova.