Think it's the winter blahs making you lonely? It may actually be your genes.

Scientists now think some lucky individuals are more prone to sadness in solitude than others. About 60 million people in the U.S. feel so isolated that it's a major source of unhappiness, according to John Cacioppo, director of the University of Chicago 's Center for Cognitive and Social Neuroscience and co-author of the book "Loneliness."

Cacioppo and friends found a supposed genetic predisposition to loneliness after studying more than 8,000 people in twin and sibling studies in the Netherlands. So, curl up in a ball on the couch and cry to mom, because it's all her fault!

The study also found that men and women deal with disconnection differently. Women are more apt to stop the slide into seclusion by having pals or pets. Men, on the other hand, watch sports or surf the Web.

You may be thinking, "So what?" The big deal is that living with limited social interaction can be as detrimental to your health as smoking a pack of cigarettes a day, Cacioppo said. It affects your sleep, diet and aging process. So make friends -- or die!

All personality traits can be attributed to nature or nurture, meaning that we're born with some and learn others from the environment around us. Some psychologists say it's impossible to tell which really determines something like loneliness.

But whether you have your parents or living in a van down by the river to thank, you can lessen loneliness by simply remembering a time when you had friends. Other researchers found that nostalgia increases individuals' senses of social support, making them feel less isolated. If that mental trick doesn't work, form real friendships (your 5,000 fans on MySpace don't count), volunteer, or say "hi" to your hot neighbor.

Or, stay alone and sing the blues with the puppet Kim Jong-il from "Team America."

Tell us: How do you stop feeling lonely?