Concepts and calculations of heritability should be noted

The concept and calculation of heritability should be noted as follows:

Hereditability refers to the ratio of the variance of heritability to the variance of the phenotype, which indicates the relative ability of the quantitative traits to be transmitted from the parents to the offspring. Generally, it is expressed by a piece, and its formula is: genetic variance (V)=additive variance (V)+dominant variance (V)+superior variance (V) in the formula, "is the variance of the cumulative effect of multiple genes, and it is the part that can be fixed hereditary: V is the variance of the dominant effect of the genes, and it will be disappeared with the enhancement of generations, and it is the part that can't be fixed hereditary.

And V, and V, are likewise not heritable. Thus, heritability in the narrow sense is the ratio of additive variance to phenotypic variance, and heritability estimates are derived from prevalence estimates in specific populations in specific environments, and are not appropriate for extrapolation to other populations and other environments; at the same time, heritability is a population statistic, and is not equal to the exact heritability of an individual.

If the heritability of a disease is 50%, it is not possible to say that half of a patient's disease is determined by genetic factors and half by environmental factors, but it should be said that half of the total variation in this disease is related to genetic variation and half is related to environmental variation. Estimates of heritability are appropriate only for diseases in which there is no genetic heterogeneity and in which there is no principal gene effect.

If there is a dominant principal gene in the polygenes that cause the disease, the estimated heritability can exceed 100%; if the principal gene is recessive, the heritability estimated by the siblings of the first witness can be higher than the heritability estimated by the parents or children. Therefore, the heritability is only appropriate if the heritabilities estimated by siblings, parents and children are similar. It can also be argued that the occurrence of the disease may be the result of polygenic inheritance.