The same fact of heredity of "constitution" is demonstrated in Weinberg's Table C 8 showing the age at death of the parents and the mortality of the children up to the age of 20. It is based on the same material as Table 7 and proves: "With the increasing age of the parents child mortality decreases, especially so in the case of the children of the tuberculous, and the number of children reaching the age of sexual maturity increases correspondingly."
Age at Death of Parents and Mortality of the Children up to the Age of 20 (including Still-born).
| Non-tuberculous. | Tuberculous. |
| Deaths per 100 living-born children: | |
 | |
| Age at death of father of mother | of father of mother |
Figure C 8.
The same is proved by the two Tables C 9 and 10 by Ploëtz referring to age at death of fathers and mothers and child mortality up to the age of five years. Very striking in both these tables is the extremely low mortality of the offspring of the parents with the greatest longevity.
Table C 11 by Weinberg: Hereditary of the disposition to beget twins (Archiv für Rassen & Gesellschafts Biologie VI. 1909) is remarkable. "The difference in favour of sisters speaks for Mendel's law of dominance and recessivity. The more twins a woman has borne, the more frequently the same phenomena is found in her nearest female relations." That the mortality among twins is very great is a well-known fact.
Inheritance of Tendency to Bear Twins.
About 2,000 families from Würtemberg family registers (after Weinberg).
In every 100,000 Births Twin Births occur in the following numbers: