Cases classified as 'non-heritable' may in fact include a proportion of heritable cases: ∼15 20% of unilateral cases are thought to be heritable, though only some will be recognised as such.
Human height is highly heritable, and in fact, the first studies of heritability examined human height.
While the risk for hip fracture is partly heritable [174], the fact that many common genetic variants have modest effects on fracture risk [175] and that these are pleiotropic [176] is consistent with the data presented here.
However, this theoretical block imposed on Lamarckian transmission does not preclude actions at the molecular level from having a heritable effect, and in fact my paper here relies on actions of this sort.
Notably, studies estimating heritability using such approaches need to account for the fact that heritability within a population does not equate to heritable differences between populations.
Recent work in epigenetics shows that epigenetic changes can, in fact, increase the heritable phenotypic variation available to natural selection (Holeski et al. 2012; Liebl et al. 2013).
Moreover, the fact that these heritable markers do not parse T. cruzi strains along the same lines as traditional typing methods is strongly suggestive of genetic exchange playing a major role in T. cruzi population structure and biology.
Nor does he mention, even in passing, the question of heritable mental illness, or the fact that Hemingway's father took his own life, as later did his sister, his brother and his granddaughter.
Their importance is emphasized by the fact that over 20 heritable human diseases have been attributed to malfunctioning PDZ containing proteins or their ligands [6], [7].
Nonetheless, more can be gleaned from quantitative genetic research, such as twin studies that compare identical and fraternal twins, than the mere fact that they are heritable.
