What an important topic, Toby!

I did some research about the "average of 5"-idea and here are some critical thoughts about it:

Childhood relationships have a bigger impact than current ones since we learn so much in the first few years of our life

Our extended network (way beyond 5 people) matters a lot, too (there's research about how people's risk of obesity increases if their friend's friends are obese --> https://www.nejm.org/doi/full/10.1056/NEJMsa066082).

Thanks for your thoughtful take on this quote.