When it comes to love, there are no hard and fast rules though many people follow the age-old theory that opposites attract.

虽然许多人都遵循“相异相吸”这一老话，但情场上其实并没有铁的法则。

But now a study has found that more often that not, similarity rules the day.

Researchers at Berkeley found that people are drawn¹ to potential romantic partners if they are of their own or similar league and desirability, which they called the 'matching hypothesis'.

Of course personality traits（个性品质） and common interests play a factor but for that instant attraction, like is drawn towards like, putting paid to the phrase, 'You're out of my league'.

For their research, the authors of the study turned - as most singletons（单件物品） do today - to online dating sites.

They measured the popularity of more than 3,000 heterosexual（异性恋的） users of a site and looked at the popularity of each.

Popularity was defined by the number of opposite-sex individuals who had sent unsolicited（未经请求的） messages to a user.

Analyses indicated that high-popularity users contacted other popular users at a rate greater than would be expected by chance.

Similarly, the less popular users of the site also contacted other low-popularity users.

The researchers then conducted a follow-up study of more than a million users and found a similar result - when it comes to dating, potential mates stick to someone in their own league.

The authors found that: 'Individuals on the dating market will assess their own self-worth and select partners whose social desirability approximately equals their own.

'Using data collected in the laboratory and from users of a popular online dating site, the authors found evidence for matching based on self-worth, physical attractiveness, and popularity, but to different degrees and not always at the same stage of the dating process.

'The most striking prediction is that undesirable² individuals will choose undesirable partners.'