It's the holiday season; a time when we are all supposed to get together with friends and family and enjoy ourselves. For people who feel left out, this is also a time to feel very lonely. Why do some people tend to feel more lonely than others?
John Cacioppo and William Patrick recently published a book entitled Loneliness: Human Nature and the Need for Social Connection. I read an article on CNN that reports the release of this book and discusses the components that cause variation in the feelings loneliness among individuals. Cacioppo is a professor in the Department of Psychology at the University of Chicago and his research indicates that loneliness variation is about 50% genetic, 50% environmental.
What does it mean that loneliness is 50% genetic? Does it mean that 50% of lonely people feel that way because of their genes? Does it mean half of everyone's feelings of loneliness are due to genetics? I read some of Cacioppo's primary research to flesh out what this number means.
The 50% statistic comes from a large twin and sibling study carried out the the Netherlands. First I will go over how this number is determined, then I will discuss the caveats we must consider when interpreting this 50% number.