There are several universal physical features of attractiveness:

1. Clear skin
   It is possible that this is a universal physical feature of attractiveness because a clear skin indicates good health, making mating more viable. This is an evolutionary reason why clear skin is attractive.
2. Symmetry
   It is possible that this is a universal physical feature of attractiveness because symmetry indicates developmental stability, which is an indication for good health. This is an evolutionary reason why symmetry is attractive.
3. Average faces
   It is possible that this is a universal physical feature of attractiveness because average faces are less likely to have genetic abnormalities, indicating good health (1) and because average faces are cognitively easier to process (2).

It is possible that mixed-ethnicities faces are more attractive because genetic diversity is a marker of healthy genes (1) and it is more average than a one-ethnicity face (2).

There is cultural variation in the ideal body weight of women with smaller-scale societies finding women with a higher body weight more attractive whereas societies which have been exposed to Western culture more finding women with a lower body weight more attractive. People in lower social-economic settings find heavier bodies more attractive whereas higher social-economic settings finding thinner bodies more attractive.

Body dissatisfaction and a desire for thinness are more common in societies with more exposure to Western ideals and high social-economic settings. There also is cultural variation in the preference for and kind of body decorations.

There are two effects that can influence attractiveness:

1. Propinquity effect (universal and powerful)
   This effect states that people are more likely to start a relationship (e.g. friendship) with whom they interact frequently. It operates through the mere exposure effect as higher exposure leads to familiarity (1) and easier processing (2), which results in people liking it more.
2. Similarity effect (cultural variation)
   This effect states that people are more likely to start a relationship (e.g. friendship) with people who are similar to oneself. This effect holds for individualistic cultures but not for collectivistic cultures.

It is possible that the similarity effect does not hold for collectivistic cultures because of a different stance towards strangers and lower relational mobility.

Attractive people are seen as having more positive qualities as demonstrated by the halo effect. This effect does not hold in cultures with low relational mobility. The residential context in which a person lives or the fact whether a person moves a lot influences the kind of relationships a person has.

Every relationship consists of one or more parts of the relational model typology:

1. Communal sharing (e.g. family dinner)
   This type of relationship is characterized by taking what you need (1) and the absence of recordkeeping (2). It is more prevalent in foraging societies with little or no surplus.
2. Authority ranking (e.g. military)
   This type of relationship is characterized by privileges and prestige for high-standing members (1) and protection and care for low-standing members (2). It is more prevalent in hierarchical societies.
3. Equality matching (e.g. dinner invitations)
   This type of relationship is characterized by tit-for-tat (1), recordkeeping (2) and a focus on balance and reciprocity (3). It is more prevalent in subsistence societies with a surplus.
4. Market pricing (e.g. property exchange)
   This type of relationship is characterized by proportionality and ratio (1), a cost-benefit analysis (2) and the irrelevance of status (3). It is more prevalent in individualistic societies.

Simpático refers to a relational style in which there is an emphasis on maintaining harmonious relationships and making excessive displays of graciousness (1), hospitality (2) and personal harmony (3). It is most prevalent in Latin America and there is a great emphasis on socializing with others.

Friendships are universal although the nature and the meaning of friendship vary across cultures. There are several differences between friendships and enemies between independent and interdependent selves:

Romantic love is universal although the meaning and display of romantic love differs across cultures. Parental love may exist because it increases the survival chance of the offspring as infants have a long period of dependency. Romantic love may exist because it increases the survival chance of the offspring as two parents might be able to provide better care than one parent.

Arranged marriages tend to fare better than love-marriages and this might be because of a self-fulfilling prophecy (1), cognitive dissonance (2), the standard of comparison (3) and social and cultural support (4).
The idealization of the partner may be a way to love the other person in love marriages as unlovable characteristics are largely ignored.