Matrilineal diversity and population history of Norwegians.

BACKGROUND: While well known for its Viking past, Norway's population history and the influences that have shaped its genetic diversity are less well understood. This is particularly true with respect to its demography, migration patterns, and dialectal regions, despite there being curated historical records for the past several centuries. In this study, we undertook an analysis of mitochondrial DNA (mtDNA) diversity within the country to elaborate this history from a matrilineal genetic perspective. METHODS: We aggregated 1174 partial modern Norwegian mtDNA sequences from the published literature and subjected them to detailed statistical and phylogenetic analysis by dialectal regions and localities. We further contextualized the matrilineal ancestry of modern Norwegians with data from Mesolithic, Iron Age, and historic period populations. RESULTS: Modern Norwegian mtDNAs fell into eight West Eurasian (N, HV, JT, I, U, K, X, W), five East Eurasian (A, F, G, N11, Z), and one African (L2) haplogroups. Pairwise analysis of molecular variance (AMOVA) estimates for all Norwegians indicated they were differentiated from each other at 1.68% (p < 0.001). Norwegians within the same dialectal region also showed genetic similarities to each other, although differences between subpopulations within dialectal regions were also observed. In addition, certain mtDNA lineages in modern Norwegians were also found among prehistoric and historic period populations, suggesting some level of genetic continuity over hundreds to many thousands of years. CONCLUSIONS: This analysis of mtDNA diversity provides a detailed picture of the genetic variation within Norway in light of its topography, settlement history, and historical migrations over the past several centuries.

Ancient human genomes suggest three ancestral populations for present-day Europeans.

We sequenced the genomes of a ∼7,000-year-old farmer from Germany and eight ∼8,000-year-old hunter-gatherers from Luxembourg and Sweden. We analysed these and other ancient genomes with 2,345 contemporary humans to show that most present-day Europeans derive from at least three highly differentiated populations: west European hunter-gatherers, who contributed ancestry to all Europeans but not to Near Easterners; ancient north Eurasians related to Upper Palaeolithic Siberians, who contributed to both Europeans and Near Easterners; and early European farmers, who were mainly of Near Eastern origin but also harboured west European hunter-gatherer related ancestry. We model these populations' deep relationships and show that early European farmers had ∼44% ancestry from a 'basal Eurasian' population that split before the diversification of other non-African lineages.

Impact of cultural background on fundamental movement skill and its correlates.

Children's fundamental movement skill levels (FMS) predict moderate-to-vigorous physical activity (MVPA). Asian children have been reported as less active than English-Europeans, possibly due to poorer skills. This study compared the FMS of children from Culturally and Linguistically Diverse (CALD) backgrounds and examined FMS correlates. A total of 261 children (122 males) aged 9-to-11 years were divided based on language spoken at home: English-European (n = 105) and Asian (n = 156). Height, mass, FMS (Test of Gross Motor Development-2), MVPA (accelerometer) and cardio-respiratory fitness (20m multistage shuttle run) were directly measured. Sex, age, language and perceived sport competence (CY-PSPP) were self-reported. Independent sample t-tests assessed age, BMI, FMS and perception by CALD group. Linear mixed models examined FMS correlates. Asian-speaking children had lower object control skill (35.5 v 37.2; CI [0.17, 3.18]; p < 0.03) compared to English-European- children, but no between-group differences in locomotor skills were observed. Fitness, physical activity and sport competence perception were positively associated with object control, yet adjusting for these variables (and age and BMI) did not remove the CALD effect (B = -2.02, SE = 0.69, p = 0.004). Cultural factors may affect object control competence in Asian-Australian children.

Genetic diversity in Svaneti and its implications for the human settlement of the Highland Caucasus.

OBJECTIVES: In this study, we characterized genetic diversity in the Svans from northwestern Georgia to better understand the phylogeography of their genetic lineages, determine whether genetic diversity in the highland South Caucasus has been shaped by language or geography, and assess whether Svan genetic diversity was structured by regional residence patterns. MATERIALS AND METHODS: We analyzed mtDNA and Y-chromosome variation in 184 individuals from 13 village districts and townlets located throughout the region. For all individuals, we analyzed mtDNA diversity through control region sequencing, and, for males, we analyzed Y-chromosome diversity through SNP and STR genotyping. The resulting data were compared with those for populations from the Caucasus and Middle East. RESULTS: We observed significant mtDNA heterogeneity in Svans, with haplogroups U1-U7, H, K, and W6 being common there. By contrast, ∼78% of Svan males belonged to haplogroup G2a, with the remainder falling into four other haplogroups (J2a1, I2, N, and R1a). While showing a distinct genetic profile, Svans also clustered with Caucasus populations speaking languages from different families, suggesting a deep common ancestry for all of them. The mtDNA data were not structured by geography or linguistic affiliation, whereas the NRY data were influenced only by geography. DISCUSSION: These patterns of genetic variation confirm a complex set of geographic sources and settlement phases for the Caucasus highlands. Such patterns may also reflect social and cultural practices in the region. The high frequency and antiquity of Y-chromosome haplogroup G2a in this region further points to its emergence there.

Heterogeneous methodology of racial/ethnic classification may be responsible for the different risk assessments for prostate cancer between Black and White men in Brazil.

OBJECTIVES: To evaluate if the different results of prostate cancer risk between black and white Brazilian men may be associated with the varying methodology used to define participants as either Blacks or Whites. PATIENTS AND METHODS: We evaluated median PSA values, rate of PSA level ≥ 4.0 ng/ mL, indications for prostate biopsy, prostate cancer detection rate, biopsy/cancer rate, cancer/biopsy rate, and the relative risk of cancer between blacks versus whites, blacks versus non-blacks (browns and whites), non-whites (browns and blacks) versus whites, African versus non-African descendants, and African descendants or blacks versus non-African descendants and non-blacks. RESULTS: From 1544 participants, there were 51.4% whites, 37.2% browns, 11.4% blacks, and 5.4% African descendants. Median PSA level was 0.9 ng/mL in whites, browns, and non-African descendants, compared to 1.2 ng/mL in blacks, and African descendants or blacks, and 1.3 ng/mL in African descendants. Indications for prostate biopsy were present in 16.9% for African descendants, 15.9% of black, 12.3% of white, 11.4% for non-African descendants, and 9.9% of brown participants. Prostate cancer was diagnosed in 30.3% of performed biopsies: 6.2% of African descendants, 5.1% of blacks, 3.3% of whites, 3.0% of non-African descendants, and 2.6% of browns. CONCLUSIONS: Median PSA values were higher for Blacks versus Whites in all classification systems, except for non-white versus white men. The rate of prostate biopsy, prostate cancer detection rate, and relative risk for cancer was increased in African descendants, and African descendants or blacks, compared to non-African descendants, and non-African descendants and non-blacks, respectively.

Recent radiation within Y-chromosomal haplogroup R-M269 resulted in high Y-STR haplotype resemblance.

Y-chromosomal short tandem repeats (Y-STRs) are often used in addition to Y-chromosomal single-nucleotide polymorphisms (Y-SNP) to detect subtle patterns in a population genetic structure. There are, however, indications for Y-STR haplotype resemblance across different subhaplogroups within haplogroup R1b1b2 (R-M269) which may lead to erosion in the observation of the population genetic pattern. Hence the question arises whether Y-STR haplotypes are still informative beyond high-resolution Y-SNP genotyping for population genetic studies. To address this question, we genotyped the Y chromosomes of more than 1000 males originating from the West-European regions of Flanders (Belgium), North-Brabant and Limburg (the Netherlands) at the highest resolution of the current Y-SNP tree together with 38 commonly used Y-STRs. We observed high resemblance of Y-STR haplotypes between males belonging to different subhaplogroups of haplogroup R-M269. Several subhaplogroups within R-M269 could not be distinguished from each other based on differences in Y-STR haplotype variation. The most likely hypothesis to explain this similarity of Y-STR haplotypes within the population of R-M269 members is a recent radiation where various subhaplogroups originated within a relatively short time period. We conclude that high-resolution Y-SNP typing rather than Y-STR typing might be more useful to study population genetic patterns in (Western) Europe.

Autosomal and uniparental portraits of the native populations of Sakha (Yakutia): implications for the peopling of Northeast Eurasia.

BACKGROUND: Sakha--an area connecting South and Northeast Siberia--is significant for understanding the history of peopling of Northeast Eurasia and the Americas. Previous studies have shown a genetic contiguity between Siberia and East Asia and the key role of South Siberia in the colonization of Siberia. RESULTS: We report the results of a high-resolution phylogenetic analysis of 701 mtDNAs and 318 Y chromosomes from five native populations of Sakha (Yakuts, Evenks, Evens, Yukaghirs and Dolgans) and of the analysis of more than 500,000 autosomal SNPs of 758 individuals from 55 populations, including 40 previously unpublished samples from Siberia. Phylogenetically terminal clades of East Asian mtDNA haplogroups C and D and Y-chromosome haplogroups N1c, N1b and C3, constituting the core of the gene pool of the native populations from Sakha, connect Sakha and South Siberia. Analysis of autosomal SNP data confirms the genetic continuity between Sakha and South Siberia. Maternal lineages D5a2a2, C4a1c, C4a2, C5b1b and the Yakut-specific STR sub-clade of Y-chromosome haplogroup N1c can be linked to a migration of Yakut ancestors, while the paternal lineage C3c was most likely carried to Sakha by the expansion of the Tungusic people. MtDNA haplogroups Z1a1b and Z1a3, present in Yukaghirs, Evens and Dolgans, show traces of different and probably more ancient migration(s). Analysis of both haploid loci and autosomal SNP data revealed only minor genetic components shared between Sakha and the extreme Northeast Siberia. Although the major part of West Eurasian maternal and paternal lineages in Sakha could originate from recent admixture with East Europeans, mtDNA haplogroups H8, H20a and HV1a1a, as well as Y-chromosome haplogroup J, more probably reflect an ancient gene flow from West Eurasia through Central Asia and South Siberia. CONCLUSIONS: Our high-resolution phylogenetic dissection of mtDNA and Y-chromosome haplogroups as well as analysis of autosomal SNP data suggests that Sakha was colonized by repeated expansions from South Siberia with minor gene flow from the Lower Amur/Southern Okhotsk region and/or Kamchatka. The minor West Eurasian component in Sakha attests to both recent and ongoing admixture with East Europeans and an ancient gene flow from West Eurasia.

Genetic affinities of Ukrainians from the maternal perspective.

The area of what is now the Ukraine has been the arena of large-scale demographic processes that may have left their traces in the contemporary gene pool of Ukrainians. In this study, we present new mitochondrial DNA data for 607 Ukrainians (hypervariable segment I sequences and coding region polymorphisms). To study the maternal affinities of Ukrainians at the level of separate mitochondrial haplotypes, we apply an original technique, the haplotype co-occurrence analysis. About 20% of the Ukrainian maternal gene pool is represented by lineages highly specific to Ukrainians, but is scarcely found in other populations. About 9% of Ukrainian mtDNA lineages are typical for peoples of the Volga region. We also identified minor gene pool strata (1.6-3.3%), each of which is common in Lithuanians, Estonians, Saami, Nenets, Cornish, and the populations of the North Caucasus.

A 3-dimensional anthropometric evaluation of facial morphology among Chinese and Greek population.

INTRODUCTION: The use of 3-dimensional (3D) facial imaging has taken greater importance as orthodontists use the soft tissue paradigm in the evaluation of skeletal disproportion. Studies have shown that faces defer in populations. To date, no anthropometric evaluations have been made of Chinese and Greek faces. AIM: The aim of this study was to compare facial morphologies of Greeks and Chinese using 3D facial anthropometric landmarks. MATERIALS AND METHODS: Three-dimensional facial images were acquired via a commercially available stereophotogrammetric camera capture system. The 3dMD face system captured 245 subjects from 2 population groups (Chinese [n = 72] and Greek [n = 173]), and each population was categorized into male and female groups for evaluation. All subjects in the group were between 18 and 30 years old and had no apparent facial anomalies. Twenty-five anthropometric landmarks were identified on the 3D faces of each subject. Soft tissue nasion was set as the "zeroed" reference landmark. Twenty landmark distances were constructed and evaluated within 3 dimensions of space. Six angles, 4 proportions, and 1 construct were also calculated. Student t test was used to analyze each data set obtained within each subgroup. RESULTS: Distinct facial differences were noted between the subgroups evaluated. When comparing differences of sexes in 2 populations (eg, male Greeks and male Chinese), significant differences were noted in more than 80% of the landmark distances calculated. One hundred percent of the angular were significant, and the Chinese were broader in width to height facial proportions. In evaluating the lips to the esthetic line, the Chinese population had more protrusive lips. CONCLUSIONS: There are differences in the facial morphologies of subjects obtained from a Chinese population versus that of a Greek population.

Correlation of different cephalometric measurements to define facial type.

The aim of this study was to analyze a possible correlation of different cephalometric measurements to define facial type and to evaluate the best measurement for diagnosis. The sample consisted of 95 lateral cephalograms of caucasian patients with normal occlusion, aged between 15 years and two months and 21 years and four months, of which 54 were male and 41 female. The facial types were divided into dolichofacial, mesofacial and brachyfacial, according to the standards stated by different authors, and a relationship among them was investigated using the Kappa and Total agreement methods. The highest agreement found was between FMA and SN.GoGn; the lowest was between SN. Gn and VERT index. According to literature review and the interpretation of the results, SN.GoGn appears to be the best measurement to define facial type.

Substantial variation in qPCR measured mean blood telomere lengths in young men from eleven European countries.

OBJECTIVES: Telomeres, repetitive DNA sequences found at the ends of chromosomes, shorten with age in proliferating human tissues and are implicated in senescence. Previous studies suggest that shorter telomeres impair immune and cardiovascular function and result in increased mortality. Although few, prior studies have documented ethnic/population differences in human telomere lengths. The nature and cause(s) of these population differences remain poorly understood. METHODS: Here, we extend the work of Salpea et al. (2008) by reporting variation in mean blood telomere lengths (BTL) from 765 individuals from 14 study centers across 11 European countries. Subjects are male students (ages 18­28), half of whom had fathers with myocardial infarction before 55 and the remainder age-matched controls. Controlling for age and case­control status, telomere lengths averaged 10.20 kilobases (interpolated from qPCR measures) across study centers and ranged from 5.10 kilobases in Naples, Italy to 18.64 kilobases in Ghent, Belgium--a greater than threefold difference across populations. These population level differences in BTLs were neither explained by national level measures of population genetic structure nor by national level ecological analysis of indices of infection/economic status. CONCLUSIONS: These findings suggest considerable population variation in BTL in Europe that is not obviously a result of broad measures of population structure or infection/economic exposure measured in early life or in adulthood.Studying telomere dynamics in a wider variety of populations, and with greater attention to life-cycle dynamics, will be important to help elucidate the causes and possible consequences of human population variation in telomere length.

Predominance of eyes and surface information for face race categorization.

Faces can be categorized in various ways, for example as male or female or as belonging to a specific biogeographic ancestry (race). Here we tested the importance of the main facial features for race perception. We exchanged inner facial features (eyes, mouth or nose), face contour (everything but those) or texture (surface information) between Asian and Caucasian faces. Features were exchanged one at a time, creating for each Asian/Caucasian face pair ten facial variations of the original face pair. German and Korean participants performed a race classification task on all faces presented in random order. The results show that eyes and texture are major determinants of perceived biogeographic ancestry for both groups of participants and for both face types. Inserting these features in a face of another race changed its perceived biogeographic ancestry. Contour, nose and mouth, in that order, had decreasing and much weaker influence on race perception for both participant groups. Exchanging those features did not induce a change of perceived biogeographic ancestry. In our study, all manipulated features were imbedded in natural looking faces, which were shown in an off-frontal view. Our findings confirm and extend previous studies investigating the importance of various facial features for race perception.

Genetic evidence of shared ancestry among diverse ethno-linguistic human populations of Himachal Pradesh.

In Indian montane system, human populations often exhibit an unparallel social organization where inter-caste marriages are still not common. This attribute affects the demography and population genetic structure of the resident populations. Further, human populations residing in the mountains in India are poorly studied for their genetic make-up and allele distribution patterns. In the present study, we genotyped 594 unrelated individuals using PowerPlex® 21 System (Promega, USA) from eight different populations belonging to 12 districts of Himachal Pradesh which differed in ethnicity, language, geography and social organization. Altogether, we obtained 1415 alleles with a mean of 8.84 ± 0.26 alleles per locus and 0.80 mean observed heterozygosity. Locus Penta E showed the highest combined power of discrimination and was found most informative for forensic purposes. Interestingly, phylogenetic analysis grouped the populations of Rajputs, Scheduled castes and Brahmins into one cluster, which indicated a deep genetic admixture in the ancestral populations. This study documents the first-ever report on the population genetic assignment of various castes in Himachal Pradesh and unveils the facts of cryptic gene flow among the diverse castes in the northern hilly state of India. Our results showed a genetic relationship among the various ethno-linguistically diverse populations of India.

Sources of self-categorization as minority for mixed-race individuals: Implications for affirmative action entitlement.

Multiracial individuals are in the unique position of being able to categorize themselves as members of multiple racial groups. Drawing on self-categorization theory, we suggest that similarity to the minority ingroup depends on self-perceptions of physical appearance and connectedness to the minority ingroup. Moreover, we argue that similarity to the ingroup determines self-categorization as minority, which predicts category-based entitlements such as perceived eligibility for minority resources (e.g., affirmative action). Using path analysis, we found support for this model on a convenience sample of 107 mixed-race minority-White participants. The results suggest that affective processes rather than observable characteristics such as prototypical physical appearance better predict self-categorization among mixed-race individuals.

In search of the pre- and post-neolithic genetic substrates in Iberia: evidence from Y-chromosome in Pyrenean populations.

The male-mediated genetic legacy of the Pyrenean population was assessed through the analysis of 12 Y-STR and 27 Y-SNP loci in a sample of 169 males from 5 main geographical areas in the Spanish Pyrenees: Cinco Villas (Western Pyrenees), Jacetania and Valle de Arán (Central Pyrenees) and Alto Urgel and Cerdaña (Eastern Pyrenees). In the Iberian context, the Pyrenean samples present some specificities, being characterizeded by a high proportion of chromosomes R1b1b2-M269 (including the usually uncommon R1b1b2d-SRY(2627) and R1b1b2c-M153 types) or I2a2-M26 and low proportions of other haplogroups. Our results indicate that an old pre-Neolithic substrate is preponderant in populations of the whole Pyrenean fringe. However, AMOVA revealed a high level of substructure within Pyrenean populations, partially explained by drift effects as well as by the signature of an ancient genetic differentiation between Western and Eastern Pyrenees.

Biohistorical approaches to "race" in the United States: Biological distances among African Americans, European Americans, and their ancestors.

Folk taxonomies of race are the categorizations used by people in their everyday judgments concerning the persons around them. As cultural traditions, folk taxonomies may shape gene flow so that it is unequal among groups sharing geography. The history of the United States is one of disparate people being brought together from around the globe, and provides a natural experiment for exploring the relationship between culture and gene flow. The biohistories of African Americans and European Americans were compared to examine whether population histories are shaped by culture when geography and language are shared. Dental morphological data were used to indicate phenotypic similarity, allowing diachronic change through United States history to be considered. Samples represented contemporary and historic African Americans and European Americans and their West African and European ancestral populations (N = 1445). Modified Mahalanobis' D(2) and Mean Measure of Divergence statistics examined how biological distances change through time among the samples. Results suggest the social acceptance for mating between descendents of Western Europeans and Eastern and Southern European migrants to the United States produced relatively rapid gene flow between the groups. Although African Americans have been in the United States much longer than most Eastern and Southern Europeans, social barriers have been historically stronger between them and European Americans. These results indicate that gene flow is in part shaped by cultural factors such as folk taxonomies of race, and have implications for understanding contemporary human variation, relationships among prehistoric populations, and forensic anthropology.

The foundation of modern racial categories and implications for research on black/white disparities in health.

The persistence of black/white disparities in health outcomes has led some to question the approaches public health, biomedical and clinical researchers use to classify, describe, and analyze race. Although these fields appear ready for the emergence of new strategies for studying race, they must first develop a solid understanding of the historical bases for the concept. This article adds to the health disparities discourse by explaining the origins of the US race and ethnicity concepts and clarifying ways in which race is 'real.' The idea of distinct and hierarchically valued races is a dominant, though problematic paradigm for explaining human diversity. We propose that the construct of race is inseparable from the term's origins and, in research must be treated as such. Doing so appropriately may enhance cross-disciplinary efforts to target the fundamental causes of racial disparities in health. We draw on multi-disciplinary research to explain how race became fixed within the American mind, describe how it structures human interactions, and highlight limitations of the official racial/ethnic categories enumerated by the US Office of Management and Budget.

Do black/white differences in telomere length depend on socioeconomic status?

Social and economic disadvantage are hypothesized to increase the risk of disease and death via accelerated biological aging. Given that US blacks are socially and economically disadvantaged relative to whites, health disparities scholars expected that blacks would have shorter telomere length-a biomarker of cell aging-than whites. Yet the majority of studies have found that blacks have longer telomere length than whites. Using data from the National Health and Nutrition Examination Survey (n = 3,761; 28.3% non-Hispanic black, 71.7% non-Hispanic white), we found that leukocyte telomere length was 4.00% (95% CI: 1.12%, 6.87%) longer among blacks compared to whites in the full sample, but differences were greatest among those with lower SES (5.66%; 95% CI: 0.10%, 10.32%), intermediate among those with middle SES (4.14%; 95% CI: 0.05%, 8.24%), and smallest among those with higher SES (2.33%; 95% CI: -3.02%, 7.67%). These results challenge purely genetic explanations for race differences in telomere length and point to a potential social-environmental cause of longer telomere length in US blacks.

Socially Assigned Race and Diabetes: Findings from the Arizona Behavioral Risk Factor Surveillance System, 2013-2014.

Socially assigned race, the racial/ethnic categorization of individuals by others, may serve as the basis for differential or unfair treatment. Latinxs are commonly socially assigned to a race/ethnicity with which they do not self-identify. However, it is unclear the degree to which self-identified Latinxs who are socially assigned as white or Latinx may differentially predict health outcomes beyond general health status and healthcare utilization. We examine the association between socially assigned race and type 2 diabetes mellitus (T2DM). Data from the Arizona's Behavioral Risk Factor Surveillance System (2013, 2014) was used in a cross-sectional analysis (restricted to Latinxs and non-Hispanic whites; N = 8370) to examine the association between self-identified (SI) and socially assigned (SA) race/ethnicity agreement and T2DM. Latinxs were categorized according to SI-SA race/ethnicity agreement: discordant (SI-SA, different) and concordant (SI-SA, same). T2DM was based on self-reported physician diagnosis. Data were analyzed using Poisson regression models to estimate prevalence ratios (PR) and 95% confidence intervals (CI). Latinxs comprised 28.5% of our sample, of which, 18.5% was discordant and 81.5% was concordant. In fully adjusted models, concordant Latinxs were more likely to have T2DM than whites (aPR 2.01, 95% CI 1.44, 2.82). There were no significant differences in T2DM between discordant Latinxs and whites. Our results suggest that socially assigned race is an understudied determinant of health and may further understanding of the impact of racial stratification on Latinx health inequities. Additional research examining socially assigned race and other health outcomes are warranted to gain further insight of the biological impact of racialized lived experiences.

Using "socially assigned race" to probe white advantages in health status.

OBJECTIVES: We explore the relationships between socially assigned race ("How do other people usually classify you in this country?"), self-identified race/ethnicity, and excellent or very good general health status. We then take advantage of subgroups which are discordant on self-identified race/ethnicity and socially assigned race to examine whether being classified by others as White conveys an advantage in health status, even for those who do not self-identify as White. METHODS: Analyses were conducted using pooled data from the eight states that used the Reactions to Race module of the 2004 Behavioral Risk Factor Surveillance System. RESULTS: The agreement of socially assigned race with self-identified race/ethnicity varied across the racial/ethnic groups currently defined by the United States government. Included among those usually classified by others as White were 26.8% of those who self-identified as Hispanic, 47.6% of those who self-identified as American Indian, and 59.5% of those who self-identified with More than one race. Among those who self-identified as Hispanic, the age-, education-, and language-adjusted proportion reporting excellent or very good health was 8.7 percentage points higher for those socially assigned as White than for those socially assigned as Hispanic (P=.04); among those who self-identified as American Indian, that proportion was 15.4 percentage points higher for those socially assigned as White than for those socially assigned as American Indian (P=.05); and among those who self-identified with More than one race, that proportion was 23.6 percentage points higher for those socially assigned as White than for those socially assigned as Black (P<.01). On the other hand, no significant differences were found between those socially assigned as White who self-identified as White and those socially assigned as White who self-identified as Hispanic, as American Indian, or with More than one race. CONCLUSIONS: Being classified by others as White is associated with large and statistically significant advantages in health status, no matter how one self-identifies.