Interracial couples elicit a neural disgust response among observers – as indicated by increased insula activation.
https://www.sciencedirect.com/science/article/abs/pii/S0022103116300555Mixedrace children suffer from more health problems
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1448064/Racemixing leads to outbreeding depression & pairings of non-complementary traits.
A massively well-funded study of over 100,000 schoolchildren found that “Adolescents who identify themselves as mixed race are at higher health and behavior risk than those of 1 race.” Indeed, even when controlling for education, socioeconomic status, and other factors, there is an across-the board higher rate of health risks amongst mixed race adolescents than mono-racial adolescents.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1448064/One study found that White-Asian mixes had a 2x higher rate of being “diagnosed with a psychological disorder, such as anxiety, depression or substance abuse.”
http://www.eurekalert.org/pub_releases/2008-08/uoc--baa081108.phpA study on Black-White mixes in agreement found that ”When it comes to engaging in risky/anti-social adolescent behavior, however, mixed race adolescents are stark outliers compared to both blacks and whites.” This holds true despite being raised in similar environments to mono-racial children.
http://www.msu.edu/~renn/RHE-_mixed_race.pdfOften race-deniers and cultural Marxists will bring up Haldane’s rule, arguing that since races can mix and create fertile offspring, the genetic distance is not too great. Haldane’s rule is “when in the offspring of two different animal races one sex is absent, rare, or sterile, that sex is the heterogametic [XY] sex.”
http://www.nature.com/scitable/topicpage/haldane-s-rule-the-heterogametic-sex-1144Indeed, although Black-White mixes are not sterile and males are not absent, males (the heterogametic sex) are more rare than females.
http://www.jstor.org/pss/1537084 
