Heritability estimates for personality traits usually range from .40 to .50.
Yet a consistent finding was that virtually every
measured trait showed at least some Heritability.
So if the Heritability of shyness is estimated at 40%,
then environmental effects must be 60%.
Scientists now believe there may be more to the process of Heritability than once thought.
The reason is that it does not mention a key requirement
for natural selection, namely the requirement of Heritability.
In Nigeria, however, where people experience a more variable access to good nutrition and health care,
height has a Heritability of only 62%.
Various studies have found the Heritability of IQ to be between 0.7 and 0.8 in adults and 0.45 in childhood in the United States.
But among individuals sleeping just 5 hours a night, the Heritability of depressive symptoms was 53%
and it was 49% for those sleeping 10 hours a night.
Heritability(how much the risk of a disease is explained by genetic factors)
of type 2 diabetes has been estimated to be between 25 and 80 per cent in different studies.
Maternal effects, often assumed to be negligible, account for 20% of covariance between twins and 5% between siblings, and the effects of genes are correspondingly reduced,
with two measures of Heritability being less than 50%.
The shared maternal(fetal) environment effects, often assumed to be negligible, account for 20% of covariance between twins and 5% between siblings, and the effects of genes are correspondingly reduced,
with two measures of Heritability being less than 50.