The Theory That People Find Partners Based on Similarity

Long-term partners often share noticeable similarities in their mannerisms, style of dress, or sense of humor. People frequently find themselves drawn to others who reflect their own characteristics. This tendency to gravitate towards the familiar is a well-documented pattern in human relationships, suggesting shared traits are a foundation for connection.

The Principle of Assortative Mating

This tendency for individuals to pair up with those who are similar is known in social science as assortative mating. It describes a pattern where people select partners who share a range of characteristics, from physical traits to social status. The vast majority of human partnerships demonstrate positive assortative mating, which is the pairing of like with like.

While less common, negative assortative mating, or the pairing of individuals with opposite traits, also occurs. The balance in long-term relationships, however, overwhelmingly favors similarity. This principle suggests our choice of a partner is guided by a preference for those who mirror our own attributes.

Dimensions of Similarity in Partner Selection

The matching process in partner selection occurs across several dimensions. One category is socio-demographics, which includes variables like:

• Age
• Level of education
• Religious conviction
• Political orientation

People are statistically more likely to partner with someone who has a similar educational background and socioeconomic status, as these factors often shape life experiences and values.

Physical traits also play a part in this selection process. Individuals tend to form long-term relationships with partners who have a comparable level of physical attractiveness. This type of sorting is observed in characteristics such as height and even some facial features.

Psychological characteristics are another area of similarity. Core values, which dictate major life decisions, are often shared between partners. Personality traits, intelligence, and sense of humor also tend to align, facilitating easier communication and shared enjoyment.

Psychological Drivers of Similarity Attraction

The preference for similar partners is driven by several psychological mechanisms. The propinquity effect suggests that we are more likely to form relationships with people we are physically and socially close to. These individuals, by virtue of being in the same places, often share similar backgrounds and experiences, making connection more probable.

Interacting with someone who shares our perspectives and habits is also more efficient. This cognitive ease means that the relationship requires less mental energy to maintain. When a partner understands our viewpoint without extensive explanation, it creates a smoother and more harmonious dynamic.

A similar partner serves to validate our own life choices, beliefs, and personal characteristics. When someone we admire reflects our own traits, it can boost self-esteem and provide a sense of rightness about who we are. This validation is a rewarding experience that strengthens attraction. Subconsciously, people also exhibit a preference for things they associate with themselves, a concept known as implicit egotism.

Revisiting “Opposites Attract”

The saying that “opposites attract” holds romantic appeal, but it is largely unsupported when it comes to long-term relationship stability. While differences can create an initial spark, research shows that similarity is a more reliable predictor of lasting satisfaction. The novelty of a dissimilar partner may be exciting at first, but it can lead to conflict as differences in core values and lifestyle preferences become more apparent.

Where differences can be beneficial is in the concept of complementarity. This is when partners have different but compatible traits that balance each other out. For example, an adventurous person might pair well with a partner who is more cautious, as they can encourage each other while also providing a sense of security. This dynamic can be enriching for a relationship.

However, complementarity works best when it operates on a foundation of shared values and life goals. A talkative person might appreciate a partner who is a good listener, but if they have clashing views on family or finances, the relationship is likely to face challenges. While minor differences can add dimension to a partnership, similarity remains the basis of a strong connection.