Researchers have found that how similar you are to your partner can affect your happiness – but its complicated. Among many monogamous species, from cockatiels to cichlid fish, studies have revealed a clear pattern: it helps to be more similar to your mate.

Is it good to be similar to your partner?

Similarities in temperament are also crucial for a lasting relationship. While smaller differences in temperament are desirable to keep things fresh, extreme differences such as a very introverted and a very extroverted partner will ultimately see their differing social appetites cause problems in their relationship.

Do relationships work if you are very similar?

Dating someone very similar to you can definitely promote better understanding at times, especially in the beginning, or “adjustment period” of a new relationship, as another study found.