It has less to do with behavior than you might think.
Not everything in a relationship comes down to personality, or even behavior. A new study released on Tuesday suggests that even factors like your number of siblings can predict the success of a relationship. The study, which was conducted by sociologists at Ohio State University, examined data from 57,000 participants from 1972-2012 using the General Social Survey.
Co-author Doug Downey specified, "One argument might be that it isn’t siblings that matter, but some other difference between large families and small families….It could have been that small families are more likely to have a single parent, or have some other issue that may hurt children in their future marriage relationship." But that turned out not to be the case. According to the press briefing, controlled factors include "education, socioeconomic status, family structure, race, age at marriage, whether the respondents had children, gender role attitudes, and religious affiliation, among others" — none of which seem to explain the influence of siblings on a successful marriage.
It's more likely that siblings affect marriage by teaching spouses better sharing, communication, and compromise skills. There is a cap to the usefulness of siblings, however. Each additional sibling diminishes the likelihood of divorce by approximately 2%– until you reach seven siblings (eight kids per family, total), at which point there ceases to be a correlation between divorce and sibling number.
Downey also organized a 2004 study in which he found that kindergarten students with siblings were rated by their teachers as having better social skills than those of only children. He also found that social skills and sibling number were not correlated by the time students reached adolescence.
John Gottman, whose work was profiled at length in Malcom Gladwell's Blink, is considered a godfather of contemporary marriage prediction models. He claims to be able to predict with 83% accuracy whether or not a couple will divorce within six years on the basis of fifteen minutes of video-recorded banter. His models generally look for variables like criticism, contempt, defensiveness, and stonewalling. He also adds that stonewalling and anger predict longer term issues, with divorce an average of 16.2 years after marriage. Gottman has been criticized for reverse-engineering many of his prediction models.
What are some less traditional factors in relationship satisfaction? Some of them may surprise you. A 2005 study, for example, found that your bicycle seat may be affecting your love life. A team of researchers led by Dr. Steven Schrader, who specializes in reproductive health, found that bike seats can create small calcified masses in men's scrotums, as well as affecting libido in frequent cyclists, according to a summary by The New York Times.
Mark Zuckerberg also allegedly claimed to be able to predict the likelihood of a relationship's success based on Facebook users' behavior. His measures included friend relationships, communication patterns, and new singlehood in nodules of users.
Another unconventional predictor comes by way of Kevin Thompson, a pastor, who claims to be able to predict divorce by how newlyweds feed each other. His "findings" are hardly scientific, but they're a fun read that jibe with the more scientific work of psychologists like Gottman. Says Thompson, "The cake exchange is supposed to have a bit of 'gotcha' in it. You get me; I get you. However, some individuals ratchet up the revenge. They don’t just get even, they make sure their get back' is better….If you can't lose, you might as well not get married."