54 The Journal of Heredity 
truth holds pretty good even to the 
latest generation, especially with the 
girls. 
Brigham Young, who was born in 
Vermont in 1801, was the second presi- 
dent of the Church of Jesus Christ of 
Latter-Day Saints, and in the opinion 
of all its members was second only to 
its founder, the Prophet Joseph Smith, 
as an organizer and statesman. He led 
the people to Utah and governed them 
for more than forty years, until his 
death in 1877. In accordance with the 
early doctrine of his church, he had nine- 
teen wives, ten of whom were mothers 
of his children. The others were widows 
to whom he gave a home and protection. 
If the children of these different wives 
had inherited equally from their mother 
and father, there would have been a con- 
siderable diversity among them. Why 
is it that there is so little variation 
among them; why is it that the father 
“stamped his impress’’ on them so uni- 
formly ? 
When we answer that it is evidently 
a case of prepotency of the father, we 
only postpone the real explanation one 
step further; for prepotency is a term 
that probably covers half a dozen dif- 
ferent things. It often results from 
consanguineous marriage, but there is 
no evidence that such matings occurred 
in the ancestry of Brigham Young. It 
may also be promoted by assortative 
mating—‘‘like with like’’—and it is 
possible that marriages of that sort had 
taken place in the Young family, al- 
though the data extant do not suffice 
to make this point plain. It may also 
be due, according to present ideas, to 
a mere chance presence of a-large num- 
ber of dominant traits in one individual. 
VALUE OF PREPOTENCY 
Whatever its origin, prepotency is a 
factor of great importance to the geneti- 
cist, and the ability to control it and 
depend on it would be of great value to 
the science. This is as true of eugenics as 
of any other branch of genetics; for it 
is obvious that if we could establish 
stocks highly prepotent in some de- 
sirable character, it would be distinctly 
to the advantage of the race. 
The subject of prepotency, therefore, 
deserves careful investigation by the 
eugenicist, and for reasons stated above 
it appears to the writer that no material 
available offers such advantages as do 
the genealogies of the Mormon families. 
Aside from the fundamental advantage 
of offering data about the offspring of a 
single husband and several wives, it 
has the further important element of 
fullness and accuracy, for the Mormons 
are among the most industrious and 
careful of genealogists. As it is for 
them a duty to work for the eternal 
happiness of one’s ancestors, and as 
these ancestors must be known, if inter- 
cession is to be made for them, it results 
that every Mormon takes a practical 
interest in genealogy, and among the 
women of the church particularly, 
familiarity with genealogical methods is 
probably more widespread than among 
any other class of people in the United 
States. 
The research worker, therefore, finds 
ready to hand among the Latter-Day 
Saints a large body of material of ex- 
traordinary value, which has as yet 
scarcely been touched for the purposes 
of biological research. It seems prob- 
able that the proper use of this material 
would advance research in human 
heredity more rapidly than will any 
other American genealogical data avail- 
able to the student; and among the 
important problems on which light 
would be thrown is certainly the prob- 
lem of prepotency, which is so strik- 
ingly illustrated in the accompanying 
photograph of Brigham Young and his 
children. 
