Justin Lehmiller, Harvard University
In 1972, a study showed scientific support for the so-called “Romeo and Juliet effect”: that the more parents interfere in a couple’s relationship, the more intense their romantic bond becomes and the stronger the relationship actually gets.
Given both the name and intuitive appeal of this idea, it is perhaps not surprising to learn that this effect has been cited hundreds of times in academic journals and textbooks. In recent years, however, several scientists (myself included) have grown sceptical. It just doesn’t seem to fit with what the broader literature on social approval and relationships has reported.
For instance, I published a series of three studies over the past decade showing that when one’s family and friends do not accept or approve of one’s relationship, the health of the partners and the quality of the relationship tends to suffer. Specifically, when people perceive that their romantic relationship is marginalised, not only do they report worse physical and psychological health and less commitment to their relationship, but they also have an increased likelihood of breaking up in the next year.
In light of these results, one might reasonably predict the opposite of the Romeo and Juliet effect: when parents don’t approve of a relationship and try to interfere, that relationship is more likely to deteriorate rather than flourish.
But if this is the case, how do we explain the findings of the 1972 study? Since the Romeo and Juliet effect was first reported, no one has studied this idea using the exact same set of measures as the original researchers. A new study just published in the journal Social Psychology tried a direct replication of the original study in an attempt to see if the findings hold up.
In this replication attempt, a sample of 396 adults who were currently involved in a romantic relationship (half married, half dating) completed two surveys about four months apart. The first time, participants reported on the degree to which their parents approved of and interfered in their relationship. Four months later, participants were asked about the quality of their relationship – that is, how much love and commitment they felt.
The results shows that the more parental approval reported at beginning, the more love and commitment was reported four months later. This was true for both dating and married couples.
Also, the more parental interference at the beginning, the less love and commitment reported four months later. However, this effect only held for married couples. For dating couples, parental interference was unrelated to future relationship quality.
As you can see, the Romeo and Juliet effect as popularised by the 1972 study did not hold up a direct replication attempt. In fact, researchers found exactly the opposite of what this effect would predict.
We do not know for sure how to explain the failed replication attempt. It would not appear to be an issue with statistical power in the new study, given that the sample size was almost 400. However, it is important to remember that the replication was conducted more than 40 years after the original, and a number of cultural and other factors have changed during that time, which could be responsible for the different findings.
In light of this and a growing body of studies finding that parental disapproval is linked to breakup and other poor relationship outcomes, it seems increasingly likely that the original report of the Romeo and Juliet effect may have been a statistical fluke.
This is an excellent reminder that replication is one of the hallmarks of good science and that it is wise not to get too excited about any single finding (no matter how catchy the name or how intuitive it seems) until it has been verified. 
Justin Lehmiller, College Fellow, Harvard University
This article is republished from The Conversation under a Creative Commons license. Read the original article.