DNA phenotyping 

Due to the wide variety of appearance traits, it is easier to recognize individuals in a group of people. Facial appearance, height, pigmentation, hair morphology and density are just some of the anthropometric features that make up the physical phenotype. The accuracy of the genetic prediction of the phenotype depends on 4 factors: 
- the heritability of a trait that determines the upper limit of the accuracy of its prediction; 
- the capacity of the DNA variation analysis method, which determines the limit of explained heritability; 
- the effectiveness of statistical methods that allow to read patterns of associations between genotypes and phenotypes; 
- the size of available data sets used in predictive modeling.
 Genomic prediction of physical appearance in connection with the determination of biogeographic ancestry, sex and age enables efficient selection of research hypotheses and faster solving of the most complicated criminal cases. High heritability of biometric traits (see monozygotic twins) suggests that a future genomic predictive system will potentially allow individual identification without the need to test a reference sample. 
Pigmentation is one of the most thoroughly studied phenotypes. The diversity of eye and hair color is particularly high in European populations, while skin color varies widely in Europe, but also globally. The genetics of pigmentation is characterized by medium complexity and many genes involved in determination of pigmentation traits have already been identified. Simple predictive systems are available in forensics that enable prediction of eye, hair and skin colours. The most advanced is the HIrisPlex-S system. The HGVR group significantly contributed to the development of this predictive tool.

Human height
Much effort has been put into the identification of genes responsible for the inheritance of the body structure, especially height that shows very high heritability. Height belongs to traits with very strong variability and is a typical continuous trait. The genetics of human height is extremely complex. The phenotype is controlled by the additive effect of many thousands of DNA variants.

Facial features
Very high expectations are associated with prediction of the facial appearance. Forensic sketches have been facilitating the work of investigators for many years. The possibility of developing an accurate sketch of an unknown person based on analysis of a DNA sample could theoretically enable identification of this individual. This is because the human face is extraordinarily variable. The extreme similarity of the faces of identical twins indicates that most of this variability is genetically determined but the the genetics of facial appearance is still poorly understood. The difficulty of research is largely due to high complexity of the human face which is a multipartite trait composed of distinct features. The use of deep learning methods at the stage of phenotype analysis gives hope for the progress in research on the identification of genes responsible for shaping facial features. Learn more about DNA-based prediction of facial appearance. 
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