Arthur Brooks, president of the American Enterprise Institute, in the New York Times:
"...Many conservatives favor an explanation focusing on lifestyle differences, such as marriage and faith. They note that most conservatives are married; most liberals are not. (The percentages are 53 percent to 33 percent, according to my calculations using data from the 2004 General Social Survey, and almost none of the gap is due to the fact that liberals tend to be younger than conservatives.) Marriage and happiness go together. If two people are demographically the same but one is married and the other is not, the married person will be 18 percentage points more likely to say he or she is very happy than the unmarried person.
... Whether religion and marriage should make people happy is a question you have to answer for yourself. But consider this: Fifty-two percent of married, religious, politically conservative people (with kids) are very happy — versus only 14 percent of single, secular, liberal people without kids."