'7 4 THE MISMEASURE OF MAN
gle X from each of their parents. Occasionally, a child will receive
two Y's from his father. XYY males look like normal males, but
tend to be a little above average in height, have poor skin and may
tend, on average—though this is disputed—to be somewhat defi-
cient in performance on intelligence tests.) Based on limited obser-
vation and anecdotal accounts of a few XYY individuals, and on a
high frequency of XYY's in mental-penal institutions for the crim-
inally insane, a tale about criminal chromosomes originated. The
story exploded into public consciousness when attorneys for Rich-
ard Speck, murderer of eight student nurses in Chicago, sought to
mitigate his punishment with a claim that he was XYY. (In fact, he
is a normal XY male.) Newsweek published an article entitled "Con-
genital criminals," and the press churned out innumerable reports
about this latest reincarnation of Lombroso and his stigmata.
Meanwhile, scholarly study picked up, and hundreds of papers
have now been written on the behavioral consequences of being
XYY. A well-intentioned but, in my opinion, naive group of Boston
doctors began an extensive screening program upon newborn
boys. They hoped that by monitoring the development of a large
sample of XYY boys, they might establish whether any link existed
with aggressive behavior. But what of the self-fulfilling prophesy?
for parents were told, and no amount of scholarly tentativeness can
overcome both press reports and inferences made by worried par-
ents from the aggressive behavior manifested from time to time by
all children. And what of the anguish suffered by parents, espe-
cially if the connection be a false one—as it almost surely is.
In theory, the link between XYY and aggressive criminality
never had much going for it beyond the singularly simplistic notion
that since males are more aggressive than females and possess a Y
that females lack, Y must be the seat of aggression and a double
dose spells double-trouble. One group of researchers proclaimed
in 1973 (Jarvik et al., pp. 679-680): "The Y chromosome is the
male-determining chromosome; therefore, it should come as no
surprise that an extra Y chromosome can produce an individual
with heightened masculinity, evinced by characteristics such as
unusual tallness, increased fertility... and powerful aggressive
tendencies."
The tale of XYY as a criminal stigma has now been widely
exposed as a myth (Borgaonkar and Shah, 1974; Pyeritz et al-,