to be traceable to distinct sources on family lines are as
follows:[58]

_Physical Traits._--Character of the facial features, color of the eyes,
hair and skin, stature, weight, energy, strength, endurance, quickness,
commanding presence, vivacity of manner, general bodily soundness; also
defects of many kinds, such as those of the nervous system, of the
speech, eyes, ears, skin, also baldness, defects of the muscular system,
blood, thyroid glands, vascular system, respiratory system, digestive
system, reproductive organs; also defects and peculiarities of the
skeleton, etc. This does not mean that all shortcomings are inherited.
It does mean, however, that the type of organism is inheritable which
lacks resistance to the germs and other precipitating factors in
bringing about the disease.

_Mental Traits._--Among the mental characteristics known to arise from
traceable hereditary sources may be mentioned factors in musical
ability, artistic composition, literary ability, mechanical skill,
calculating ability, inventive ability, memory, ability to spell,
fluency in conversation, aptness in languages, military talent,
acquisitiveness, attention, story-telling, poetic ability; and, on the
other hand, insanity, feeble-mindedness of many types, epilepsy. These
are suggestive of the inheritability of many other mental traits not yet
studied.

_Moral Traits._--Among the moral traits known to possess inheritable
elements are generosity, piousness, independence, industry, will-power,
faithfulness, fairness, sociability, reliability, self-reliance,
tendency to work hard, perseverance, carefulness, impulsiveness,
temperance, high-spiritedness, joviality, benignity, quietness,
cheerfulness, hospitality, sympathy, humorousness, love of fun,
neighborliness, love of frontier life, love of travel and of adventure.
The same may be said of immoral traits, such as criminality, pauperism,
delinquency, irascibility, lying, truancy, superstition, clannishness,
secretiveness, despondency, slyness, exclusiveness, vanity, cunning,
cruelty, quickness to anger, revengefulness, etc.

[Sidenote: Distribution of Traits]

These physical, mental and moral peculiarities are not scattered evenly
through the population, but exist on certain family lines only.

For instance, one-tenth of the deaths that occur in the United States
are from tuberculosis. But this does not mean that one-tenth of all
families die of the disease. On the contrary, some