RESEARCH ARTICLE Kinship and morphological similarity in the skeletal remains of individuals with known genealogical data (Bohemia, 19th to 20th centuries): A new methodological approach Jan Cvr  cek 1,2 | Petr Velemínský 1 | Ján Dupej 2,3 | Luboš Vostrý 4 | Jaroslav Brůžek 2 1 Department of Anthropology, National Museum, Czech Republic 2 Department of Anthropology and Human Genetics, Faculty of Science, Charles University, Czech Republic 3 Department of Science and Computer Science Education, Faculty of Mathematics and Physics, Charles University, Czech Republic 4 Czech University of Life Sciences Prague, Czech Republic Correspondence Jan Cvr cek, Department of Anthropology, National Museum, Cirkusová 1740, Prague 20, Horní Po cernice, Czech Republic. Email: jan_cvrcek@nm.cz Funding information Ministry of Culture of the Czech Republic, Grant/Award Number: DKRVO 2018/17, National Museum; Grant Agency of Charles University, Grant/Award Number: GAUK 1276217; The National Agency for the Agricultural Research, Grant/Award Number: NAZV QJ1510141 Abstract Objectives: This article proposes a new approach, called the “similarity coefficient” (SC) for veri- fying family relationships from skeletal remains using nonmetric traits. Based on this method and further analyses, the authors aim to show the degree of similarity between individuals with varying degrees of kinship, including inbred individuals. Materials and Methods: Our sample includes the skeletal remains of 34 individuals with known genealogical data (four generations, 19th to 20th centuries). A total of 243 skeletal nonmetric traits were evaluated with respect to their anatomical characteristics. The SC was calculated by quantifying the agreement of trait occurrence between individuals. We also identified the traits that support the biological relationships of particular individuals by accounting for their popula- tion frequencies. Results: There was a positive correlation between the morphological similarity of biologically related individuals and their biological distance. In some cases, we found greater degree of mor- phological similarity between first cousins than among other close relatives such as parents and children. At the same time, there was no statistically significant difference in the degree of simi- larity between inbred individuals and common relatives. Proven family relationships were best reflected by cranial traits, especially bone bridges associated with the courses of blood vessels and nerves. Conclusions: The use of skeletal nonmetric traits for the detection of relatives is possible. There is a relationship between biological distance and the degree of morphological similarity in related individuals. It also appears that inbreeding, despite previous assumptions, does not lead to a significant reduction in morphological variation. KEYWORDS genealogical documented sample, inbreeding, kinship analysis, morphological nonmetric traits, similarity coefficient 1 | INTRODUCTION The identification of family relationships based on the skeleton is one of the most difficult goals to achieve in bioarcheological or forensic research (Esparza et al., 2017). Earlier, the term “kinship analysis” was frequently used in connection with this objective. However, in bioarcheology, the use of this term has been criticized (Johnson & Paul, 2015; Ensor et al., 2017). We can discuss the patterns of pheno- typic similarity and the possibilities of their use for kinship analysis (Stojanowski & Hubbard, 2017). There are two approaches to achieve this aim: DNA analysis (Ricaut et al., 2010; Deguilloux et al., 2014) and morphology. In this case, we use (a) osteological and dental nonmetric traits (NMTs) (Stojanowski & Schillaci, 2006; Paul & Stojanowski, 2015; Stojanowski & Hubbard, 2017), (b) selected bone dimensions (Carson, 2006a; Martínez-Abadías et al., 2009), and (c) genetically con- ditioned anomalies manifested in the skeleton (Anderson, 1968; Berry, 1975; Case et al., 2016). According to previous studies (Rösing, 1986, 1990; Ritschmeier et al., 1984; Ricaut et al., 2010), the greatest impor- tance is attributed to nonmetric (NM) phenotypic traits. Dental NMTs are preferred (Turner et al., 1991; Scott & Turner, 1997; Scott & Irish, Received: 14 February 2018 Revised: 20 June 2018 Accepted: 26 June 2018 DOI: 10.1002/ajpa.23683 Am J Phys Anthropol. 2018;1–16. wileyonlinelibrary.com/journal/ajpa © 2018 Wiley Periodicals, Inc. 1