suggests that people whose physical features suggest they are healthy are seen as more attractive. The theory suggests that a healthy mate is more likely to possess genetic traits related to health that would be passed on to offspring (known as indirect benefits), and also that a healthier mate may be able to provide better resources and parental investment than less healthy mates (known as direct benefits). People's tendency to consider people with facial symmetry more attractive than those with less symmetrical faces is one example. However, a test was conducted that found that perfectly symmetrical faces were less attractive than normal faces. According to this study, the exact ratio of symmetric to asymmetric facial features depicting the highest attraction is still undetermined. It has also been suggested that people are attracted to faces similar to their own as these features serve as cues of kinship. This preference for facial-resemblance is thought to vary across contexts. For example, a study by DeBruine et al. (2008) found that individuals rated faces which had been manipulated to be similar to their own as having more prosocial attributes, but were less likely to find them sexually attractive. These results support "inclusive fitness theory", which predicts that organisms will help closely related kin over more distant relatives. Results further suggest inherent mate-selective mechanisms that consider costs of inbreeding to offspring health. Increased female attraction to men in relationships A 2009 study by Melissa Burkley and Jessica Parker found that 59% of women tested were interested in pursuing a relationship with an "ideal" single man (who was, unknown to the women, fictitious). When they believed the "ideal" man was already in a romantic relationship, 90% of the women were interested in a romantic relationship. Breaking up There are several reasons that a relationship, whether friendly or romantic, may come to an end (break up). One reason derives from the equity theory: if a person in the relationship feels that the personal costs of being in the relationship outweigh the rewards there is a strong chance that this person will end the relationship. See also Bad boy (archetype) Beer goggles Dating Human bonding Interpersonal compatibility Love (scientific views) Platonic love Pratfall effect Puppy love Seduction Sexual attraction Socionics Social connection Vulnerability and care theory of love Inertia Notes References External links Interpersonal relationships Love Dating