Variation and Heritability in Hair Diameter and Curvature in an Australian Twin Sample

Yvonne Ho, Mark Brims, Dennis MCNEVIN, Tim Spector, Nicholas Martin, Sarah Medland

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Hair diameter and curvature are two characteristics of human scalp hair used in forensic contexts. While previous data show that subjective categorization of hair curvature is highly heritable, the heritability of objectively measured curvature and diameter, and variability of hair characteristics within each individual have not yet been studied. The present study measured hair diameter and curvature using an optical fiber diameter analyzer in a sample of 2,332 twins and siblings. Heritability was estimated using maximum likelihood structural equation modeling. Results show sex differences in the magnitude of genetic influence for mean diameter and curvature, with the vast majority of the variance accounted for by genetic effects in males (diameter = 86%, curvature = 53%) and females (diameter = 77%, curvature = 61%). The consistency of diameter (variance within an individual) was also highly heritable, but did not show sex limitation, with 68% of the variance accounted for by genetic factors. Moderate phenotypic correlations were seen between diameter and consistency (r = 0.3) but there was little correlation between diameter and curvature (r =-0.13). A bivariate Cholesky analysis was used to estimate the genetic and environmental correlations between hair diameter and consistency, yielding genetic correlations of r gF = 0.27 for females and r gM = 0.25 for males.
Original languageEnglish
Pages (from-to)351-358
Number of pages8
JournalTwin Research and Human Genetics
Volume19
Issue number4
DOIs
Publication statusPublished - 2016

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Hair
Optical Fibers
Scalp
Sex Characteristics

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Ho, Yvonne ; Brims, Mark ; MCNEVIN, Dennis ; Spector, Tim ; Martin, Nicholas ; Medland, Sarah. / Variation and Heritability in Hair Diameter and Curvature in an Australian Twin Sample. In: Twin Research and Human Genetics. 2016 ; Vol. 19, No. 4. pp. 351-358.
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title = "Variation and Heritability in Hair Diameter and Curvature in an Australian Twin Sample",
abstract = "Hair diameter and curvature are two characteristics of human scalp hair used in forensic contexts. While previous data show that subjective categorization of hair curvature is highly heritable, the heritability of objectively measured curvature and diameter, and variability of hair characteristics within each individual have not yet been studied. The present study measured hair diameter and curvature using an optical fiber diameter analyzer in a sample of 2,332 twins and siblings. Heritability was estimated using maximum likelihood structural equation modeling. Results show sex differences in the magnitude of genetic influence for mean diameter and curvature, with the vast majority of the variance accounted for by genetic effects in males (diameter = 86{\%}, curvature = 53{\%}) and females (diameter = 77{\%}, curvature = 61{\%}). The consistency of diameter (variance within an individual) was also highly heritable, but did not show sex limitation, with 68{\%} of the variance accounted for by genetic factors. Moderate phenotypic correlations were seen between diameter and consistency (r = 0.3) but there was little correlation between diameter and curvature (r =-0.13). A bivariate Cholesky analysis was used to estimate the genetic and environmental correlations between hair diameter and consistency, yielding genetic correlations of r gF = 0.27 for females and r gM = 0.25 for males.",
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Ho, Y, Brims, M, MCNEVIN, D, Spector, T, Martin, N & Medland, S 2016, 'Variation and Heritability in Hair Diameter and Curvature in an Australian Twin Sample', Twin Research and Human Genetics, vol. 19, no. 4, pp. 351-358. https://doi.org/10.1017/thg.2016.45

Variation and Heritability in Hair Diameter and Curvature in an Australian Twin Sample. / Ho, Yvonne; Brims, Mark; MCNEVIN, Dennis; Spector, Tim; Martin, Nicholas; Medland, Sarah.

In: Twin Research and Human Genetics, Vol. 19, No. 4, 2016, p. 351-358.

Research output: Contribution to journalArticle

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