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Among 197 inmates at Carstairs State Hospital, they found no fewer than seven XYY men, or 3.5% (as well as one XXYY). This, they estimated, was 50 to 60 times the normal incidence. To check this estimate, the Edinburgh investigators examined 266 newborn boys and 209 adult men without finding a single XYY. In a random collection of 1,500 karyotypes, they found only one XYY.
The XYY inmates averaged 6 ft. 1 in. tall, whereas the average for other Carstairs inmates was 5 ft. 7 in. In Mel bourne, Dr. Saul Wiener found that the same was true of four Australians, all XYY, who were doing time for murder, attempted murder or larceny. Dr. Mary A. Telfer of Pennsylvania's Elwyn Institute found five XYY abnormalities among 129 inmates at Pennsylvania prisons and penal hospitals selected for study because of their height.
Property Offenses. The consensus so far among the few investigators who have studied the problem is that an extra Y chromosome seems to be as sociated with below-average intelligence, tall stature and severe acne—traits that might result from the hormone-stimulating effects of the duplicated chromosome. But little more is known about the Y chromosome's effects. Dr. Wil liam Price, who works with the research group in Edinburgh, doubts that the XYY pattern can be linked with crimes of violence or sex. Among the XYY men studied at Carstairs, he points out, the proportion whose offenses were against property—such as petty theft and housebreaking—was greater than that among convicts generally.
The XYY males, according to Price, do not suffer from brain damage, epilepsy, or any recognized psychosis such as schizophrenia. They are psychopaths, also called sociopaths—"unstable and immature, without feeling or remorse, unable to construct adequate personal relationships, showing a tendency to abscond from institutions and committing apparently motiveless crimes, mostly against property."
Scotland's XYY convicts tended to get into trouble earlier (around age 13) than the average (about 18). But among their siblings there was an unusually low incidence of criminality. And in the only case so far reported of an XYY with several children, the abnormality was not transmitted: an Oregon XYY has had six sons, but all have a normal XY pattern.
* Chromosome patterns or "karyotypes" are usually made by taking white blood cells, growing them in the laboratory and dousing them with a weak salt solution. This explodes the cells, separating the chromosomes. These are stained, spread on a slide and photographed. From an enlargement, pairs of chromosomes are laboriously cut out, paper-doll fashion, lined up by size and shape in seven groups, and numbered from one to 22 (the "Denver classification"). X and Y are usually placed at the end.