[Footnote 27:  See note, infra, p. 29.]

Omitting, as in the discussion on page 24, those genealogies in which only the male line is given we have the following table: 

TABLE  VIII.
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|First  | 1-1/2 |Second | 2-1/2 | Third |Distant|
|cousins|cousins|cousins|cousins|cousins|cousins|Total
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Same-name     |   24  |   5   |  10   |   4   |   2   |   5   |  50
Different-name|   62  |  15   |  33   |  12   |  23   |  26   | 171
------------------------------------------------------------

--------
Total         |   86  |  20   |  43   |  16   |  25   |  31   | 221
------------------------------------------------------------

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It would naturally be supposed that with each succeeding degree of relationship the ratio of same-name to different-name cousin marriages would increase in geometrical proportion, viz. first cousins, 1:3; second cousins, 1:9; third cousins, 1:27, etc., but on the other hand there is the tendency for families of the same name to hold together even in migration as may be proved by the strong predominance of certain surnames in nearly every community.  So that the ratio or same-name to different-name second cousin marriage may not greatly exceed 1:4.  Beyond this degree any estimate would be pure guesswork.  However the coefficient of attraction between persons of the same surname would undoubtedly be well marked in every degree of kinship, and conversely there are few same-name marriages in which some kinship, however remote, does not exist.

The proportion of mixed generation cousin marriages (1-1/2 cousins, 2-1/2 cousins, etc.) is always smaller than the even generation marriages of either the next nearer or more remote degrees.  For example, a man is more likely to marry his first or his second cousin than either the daughter of his first cousin, or the first cousin of one of his parents, although such mixed generation marriages often take place.

The conclusions, then, in regard to the frequency of consanguineous marriage in the United States may be summarized as follows: 

1.  The frequency varies greatly in different communities, from perhaps .5 per cent of first cousin marriages in the northern and western states to 5 per cent, and probably higher, in isolated mountain or island communities.  The average of first cousin marriage in the United States is probably not greater than one per cent.

2.  The percentage of consanguineous marriages is decreasing with the increasing ease of communication and is probably less than half as great now as in the days of the stage coach.

3.  Although the number of marriageable second cousins is usually several times as great as that of first cousins, the number of marriages between second cousins is probably somewhat less than the number of marriages between first cousins, but the number of second cousin marriages combined with the number of 1-1/2 cousin marriages probably exceeds the number of first cousin marriages alone.  So that the percentage of marriages ordinarily considered consanguineous is probably between two, and two and a half.