Editing Interpersonal attraction (section)

===Evolutionary theories===
The evolutionary theory of human interpersonal attraction states that opposite-sex attraction most often occurs when someone has physical features indicating that he or she is very fertile. Considering that one primary purpose of conjugal/romantic relationships is reproduction, it would follow that people invest in partners who appear very fertile, increasing the chance of their genes being passed down to the next generation.

Evolutionary theory also suggests that people whose physical features suggest they are healthy are seen as more attractive.<ref>{{Citation|title=Healthy body, healthy face? Evolutionary approaches to attractiveness perception|url=http://dx.doi.org/10.3726/978-3-0351-0826-2/13|work=Culture and Cognition|year=2015|publisher=Peter Lang|doi=10.3726/978-3-0351-0826-2/13|isbn=978-3-0343-1558-6|access-date=2020-09-11|archive-date=2022-01-25|archive-url=https://web.archive.org/web/20220125080053/https://www.peterlang.com/document/1053163|url-status=live}}</ref> 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.<ref>{{cite journal |title = Asymmetry and Human Facial Attractiveness: Symmetry May not Always be Beautiful |last1 = Swaddle |first1 = John P. |last2 = Cuthill |first2 = Innes C. |journal = [[Proceedings: Biological Sciences]] |issn = 0962-8452 |volume = 261 |issue = 1360 |year = 1995 |pages = 111–16 |doi = 10.1098/rspb.1995.0124 |pmid = 7644543 |jstor = 50054  |bibcode = 1995RSPSB.261..111S |s2cid = 33285473 }}</ref>

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.<ref>{{cite journal | title = Social Perception of Facial Resemblance in Humans | last1 = DeBruine | first1 = Lisa M. | last2 = Jones | first2 = Benedict C. | last3 = Little | first3 = Anthony C. | last4 = Perrett | first4 = David I. | journal = Archives of Sexual Behavior | volume = 37 | issue = 1 | year = 2008 | pages = 64–77 | doi = 10.1007/s10508-007-9266-0| pmid = 18157627 | s2cid = 10772493 }}</ref>