is not inheritable, comparative infertility may be. And even then 8 or
9 per cent does not seem to be an excessively high proportion of
sterility, especially if late marriages be counted. Boudin bases his
assertion on this point on even less tenable grounds.[44] On the other
hand some writers assure us that cousin marriages are even more
prolific and less liable to sterility than the average.

[Footnote 43: See Darwin, "Marriages between First Cousins in England
and Their Effects," _Journal of Statistical Society_, June, 1875, p.
178.]

[Footnote 44: Boudin, "Croisement des familles, de races et des
espèces." In _Memoires de la Société d' Anthropologie_, vol. i, p.
518.]

The most important statistical investigation was made by G.H.
Darwin.[45] From his genealogical data he compiled the following
table:

TABLE XVI.
------------------------------------------------------------------------
| | Average | |Ave. no.
| | number | Per cent |sons to
|Number of | sons to | sterile |fertile
|marriages.| marriage. | marriages. |marriage.
------------------------------------------------------------------------
Not consanguineous | 217 | 1.91 | 15.9 | 2.26
Parents 1st cousins[A] |97 to 105 |2.07 to 1.92|14.7 to 20.9| 2.43
One parent offspring of | | | |
1st cousin marriages. | 93 | 1.93 | 17.2 | 2.34