Self-Reported Ancestry and Craniofacial SNPs Assessing Correspondence with Implications for Forensic Case Analysis and Reporting

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Kamar Afra
Michelle D. Hamilton
Bridget F. B. Algee-Hewitt


Genotype-phenotype studies increasingly link single nucleotide polymorphism (SNPs) to the dimensions of the face for presumed homogeneous populations. To appreciate the significance of these findings, it is essential to investigate how these results differ between the genetic and phenotypic profiles of individuals. In prior work, we investigated the connection between SNPs previously identified as informative of soft tissue expression and measurements of the craniofacial skeleton. Using matched genetic and skeletal information on 17 individuals who self-identified as White with presumed common continental ancestry (European), we obtained significant Spearman correlations for 11 SNPs. In the present study, we looked at self-identified ancestry to understand the intersectional background of the individual’s phenotype and genotype. We integrated our samples within a diverse dataset of 2,242 modern Americans and applied an unsupervised model-based clustering routine to 13 craniometrics. We generated a mean estimate of 69.65% (±SD = 18%) European ancestry for the White sample under an unsupervised cluster model. We estimated higher quantities of European ancestry, 88.5%–93%, for our subset of 17 individuals. These elevated estimates were of interest with respect to the distribution of population-informative SNPs; we found, for example, that one of our sampled self-identified White individuals displayed SNPs commonly associated with Latin American populations. These results underscore the complex interrelationship between environment and genetics, and the need for continued research into connections between population affinity, social identity, and morphogenetic expression.

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