Educability-and-Group-Differences-1973-by-Arthur-Robert-Jensen

228 Educability and Group Differences
OFFSPRINGS OF NEGRO-WHITE MATINGS
Theoretically, if most of the variation in intelligence is due to
additive genetic effects, the average intelligence of the offspring of
parents from each of two racial groups with different genetic
means should be approximately intermediate between the means of
the two groups. And if genetic factors were all-important, the
offsprings’ average should be the same regardless of whether the
mother or the father had the higher IQ or came from the group
with the higher mean. If the test scores of the offspring were
not independent of the mother’s race, this would constitute
evidence for non-genetic factors in racial IQ variation - provided
a crucial condition is met, viz., that the average parental IQ is
the same for either maternal or paternal racial combination.
Failure to meet this requirement makes the only published study
of this type wholly inconclusive. Willerman, Naylor, and Myrianthopoulos
(1970) compared the IQs of four-year-old children
resulting from all four of the possible combinations of matings of
Negro and white men and women. They found that the interracial
offspring of white mothers were significantly higher than of interlacial
Negro mothers. Nearly all of this effect was due to the very
low IQs of the male children of unmarried Negro mothers. Maternal
race was a significant factor in the results only among the children
of the unmarried Negro mothers, whose children, particularly the
males, had the lowest IQs. This finding accords with others showing
the greater vulnerability of males to unfavorable prenatal,
perinatal, and postnatal conditions (Jensen, 1971b). But the study
sheds little, if any, light on racial genetic differences, since there
was no measurement of the parental IQs in the two interracial
combinations.5 Persons involved in interracial marriages or matings
cannot be regarded as representative of the general population of
whites or Negroes. For example, a study (reported in Goldhammer,
1971) of racial intermarriages between 1914 and 1938 in Boston
showed that Negro grooms were occupationally well above the
average employed Negro male, whereas white grooms were
occupationally far below employed white males in general. Both
white and Negro brides in interracial marriages were occupationally
below the average of women in their respective racial groups.
In interracial marriages, the average IQ of Negro grooms is
probably higher than of white grooms. Thus the higher IQs of