Explain what behavioral geneticists mean by the term heritability and why it is frequently ...

ANSWER:
Heritability is the statistical likelihood that variations observed across individuals in a population are due to genetics. Heritability is usually presented as a ratio of the amount of variation observed in a population due to genetics relative to the total amount of variation due to both genetic and environmental influences. Heritability is a concept that is frequently misunderstood. Heritability always refers to populations, not to individuals. Saying that a trait such as shyness is 40 heritable does not say that 40 of one individuals shyness is produced by genes and the other 60 by the environment. Instead, a 0.40 heritability ratio suggests that the variations in shyness we see across the population (from very high to very low) are influenced moderately by both genetic and environmental factors.

If genes play no part in producing phenotypical differences between individuals, heritability is zero. For example, genes are responsible for us having hearts, but there is no individual variation in the population in terms of the presence of a heartwe all have one. Consequently, the heritability of having a heart is 0.0. If genes are totally responsible for all phenotypical differences between individuals, heritability is 1.0. All variation in the population in terms of having or not having a fatal neurological condition known as Huntingtons disease is entirely due to genetics. If you inherit a Huntingtons gene from one parent, you will develop the condition, so the heritability of Huntingtons is 1.0.