[Footnote 89:  Marriages of the Deaf in America, chap. v.]

[Footnote 90:  Of the 17 children of first cousins reported on my circulars as either totally or partially deaf, 9 are known to have had deaf ancestors.]

Dr. Fay found that 31 out of the 4,471 marriages of the deaf were consanguineous, but he expresses the belief that the actual number and percentage of consanguineous marriages of the deaf are larger.  The following table which combines several of Dr. Fay’s tables sets forth the main results of his work.  In each instance one or both parties to the marriage were deaf.  The totals include only those of whom information as to the offspring was available.

TABLE XXXIV.
----------------------------------------------------------
|      | Marriages |
|      | resulting |
|      |  in deaf  |
|      | offspring |  Deaf children
|Number|-----------|------------------
Consanguineous   |of    |      |    |             |Per
Marriages      |mar-  |      |Per |      |Number|Cent
of the Deaf.    |riages|Number|Cent|Number|Deaf  |Deaf
----------------------------------------------------------
First cousins       |    7 |   4  | 57.|   26 |    7 | 27. 
Second cousins      |    5 |   3  | 60.|   25 |   10 | 40. 
Third cousins       |    1 |   1  | —­ |    1 |    1 | —­
“Cousins”           |   14 |   3  | 21.|   36 |    7 | 19. 
Nephew and aunt     |    1 |   1  | —­ |    4 |    3 | 75. 
Distantly related   |    3 |   2  | 67.|    8 |    2 | 25.
----------------------------------------------------------
Total consanguineous|   31 |  14  | 45.|  100 |   30 | 30. 
Not consanguineous, |      |      |    |      |      |
or no information  |3,047 | 286  |  9.|6,682 |  558 |  8.
----------------------------------------------------------
Grand total         |3,078 | 300  | 10.|6,782 |  588 |  9.
----------------------------------------------------------
pre>
Obviously percentages based on these figures are of
little value of themselves, especially since Dr. Fay’s
cases are not entirely typical, but in general this
table points us to the same conclusion that we have
reached by other means, namely that where a tendency
toward deafness exists, a consanguineous marriage
is more likely to produce deaf children than a non-consanguineous
marriage.  If more figures were available the
percentage of deaf children would probably increase
with the nearness of consanguinity and the number
of deaf relatives, but with the present data a further
analysis has no significance.[91]
[Footnote 91:  Mr. Edgar Schuster (Biometrika,
vol. iv, p. 465) finds from Dr. Fay’s statistics
that the average parental correlation (parent and
child) of deafness is:  paternal, .54; maternal,
.535.  English statistics of deafness give: 
paternal correlation, .515; maternal, .535.  The
fraternal correlation from the American data is .74
and from the English .70.  See infra, p.
92.]
If, then, consanguineous marriages where relatives
are deaf have a greater probability of producing deaf
offspring, and also a greater probability of producing
plural deaf offspring, than ordinary marriages, and
two thirds of the congenitally deaf offspring of consanguineous
marriages do have deaf relatives, it does not seem
necessary to look beyond the law of heredity for an
explanation of the high percentage of the congenitally
deaf who are of consanguineous parentage.