How do humans recognise kin?

Kinship moderates important social outcomes, such as interpersonal violence and sexual behaviour, but how do you know who your kin are? On the surface, this appears to be a simple question, but we understand little about how humans determine who feels like family. Genetic relatedness is, in fact, only a small part of what influences our behaviour, and indirect cues such as who you've lived with and when, what you look and smell like, and what words you use to describe your relationship have profound effects on behaviour.

This project combines biological theories regarding the essential role of kinship in regulating social and sexual behaviour with advanced methods from experimental psychology, genetics, acoustics, computer graphics and experimental economics, to develop and test the first comprehensive model of human kin recognition. While the importance of this project is mainly to increase our basic understanding of human kinship perception, this information on how and why family relatedness increases proscoial behaviour and decreases sexual attractiveness will provide a scientific underpinning for applied research on situations where this is not the case, such as family violence and incest.

Our project has two main objectives. First, to build a model of human kin recognition that will help us to test ideas about the evolution of kin recognition and how kinship cues influence our behaviour towards others. Second, to produce a computer model of how family resemblance is expressed in the face, which will be used to develop novel methods for assessing family resemblance from face images and experimentally creating realistic and biologically plausible “virtual relatives” using computer graphics.

The project has completed data collection and the analysis of results and preparation of the major final manuscript for the first objective (WP1) is ongoing. The unexpected direction of this, in combination with general covid disruptions, has led to the unusual delay. The main conclusion of the research for WP1 and WP2 (relating to the first objective) is that the convergent validity of the measures commonly used to asses kin recognition is so bad as to call all research in this area into question.

The second main objective involved the dissemination of technological advances developed during the project. Those have produced a very highly used website (>262K users) for creating reproducible face stimuli and a tool for conducting complex data collection. Work packages 2 and 3 produced several papers on perceptions of facial cues of kinship, listed below. Work package 4 produced two main papers on methods for objectively assessing facial similarity, and work is ongoing to disseminate those methods as R packages.

In addition to the 40 main and incidental papers listed in the publications section, we have also published one book chapter, one popularised publication, many invited conference talks and conference posters, listed below.

The project produced several open-source tools for implementing methods developed for this project:

https://webmorph.org/ - Upload images online and measure or manipulate their appearance (262K users)
https://debruine.github.io/webmorphR/ - An R package to create scripts for manipulating face stimuli to make research more reproducible and generalisable (under submission to CRAN)
https://debruine.github.io/faux/ - An R package to simulate data for custom power analyses and other purposes (23K downloads)
https://doi.org/10.5281/zenodo.2634355 - Web-based software for managing linked data collection

The project has achieved a high level of public engagement. Our 3D image collection has been featured at the Glasgow Science Centre on several occasions for public science events. We have also demonstrated our research technology at three invited events with substantial outreach, i.e. Science Lates (Glasgow Science Centre), the ESRC Festival of Social Science and the European Researchers’ Night. We have also spoken about family resemblance and demonstrated techniques for measuring and manipulating family resemblance on several TV documentaries, listed below.

Your Face Says it All (2016) Channel 4, UK
https://youtu.be/5D8JkBjvTok
Dr DeBruine spoke on face perception generally and facial resemblance among kin.

Finding My Twin Stranger (2016) Channel 4, UK
http://www.imdb.com/title/tt6315032/
We assessed facial resemblance between doppelgängers using 2D and 3D image assessments developed for the KINSHIP project. Dr Holzleitner was featured in the documentary running the 3D camera, while Dr DeBruine was featured in the documentary explaining the science behind facial similarity metrics to the participants.

Cousins: A Wedding In The Family (2019) BBC3, UK
https://www.bbc.co.uk/programmes/p056gvhm
We created self-resembling and father-resembling images for the subject of the documentary, an 18-year-old trying to decide whether or not to pursue a cousin marriage. Dr DeBruine also spoke to her about the research on mate choice and family resemblance.

Our website, which allowed previous participants to access their 3D images and also provides info on the KINSHIP project and our research, as well as several online demos, had approximately 40,400 unique visitors since the start of the grant. However, due to increased security and privacy concerns after GDPR came in, this site has been taken down.

In summary, we estimate that our dissemination and communication activities have reached more than 20,000 members of the general public; the viewing numbers for the three TV documentaries are not possible to estimate, but the YouTube version of Finding my Twin Stranger has had 14.7M views (https://www.youtube.com/watch?v=i1nz5Bkpmcw).

Periodic Reporting for period 4 - KINSHIP (How do humans recognise kin?)

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