Attia starts Chapter 4 by pondering whether there are specific types of healthy behaviors that lead people to become centenarians. He points to examples of recent centenarians, such as Richard Overton, Henry Allingham, Jeanne Calment, Mildred Bowers, and Emma Morano, who all had unhealthy behaviors (e.g., smoking and drinking alcohol) but remained happy and healthy well past the age of 100. Given their unhealthy behaviors, luck may have played a role in their advanced age.

These anecdotes, coupled with recent research into centenarians, suggest there are no unifying healthy behaviors among this group. Instead, luck and genes may play some role. Attia notes, “being the sister of a centenarian makes you eight times more likely to reach that age yourself, while brothers of centenarians are seventeen times as likely to celebrate their hundredth birthday” (62). Most of us, however, do not have centenarians in our family history. Attia still believes we can live healthier longer even without centenarian genes.

A key observation about centenarians is that if they develop Horsemen diseases, they do so much later in life compared to the average person. Centenarians also retain high cognitive functions and the ability to do daily tasks (e.g., clip their own toenails and cook meals for themselves).