Among 43 monozygotic (MZ) and 19 dizygotic (DZ) pairs in which an index case had definite Parkinson's disease (PD), only one MZ pair was definitely concordant for PD. When pairs with questionable clinical features were included, 4 of 48 MZ and 1 of 19 DZ pairs were concordant. The frequency of PD in MZ cotwins of index cases with PD was similar to that expected in an unrelated control group matched for age and sex. Although we were unable to identify a single environmental agent, we conclude that the major factors in the etiology of PD are nongenetic.

A previous study of twins with Parkinson's disease (PD) revealed low concordance, suggesting that genetic factors play a minor role in the etiology of PD. To identify possible environmental determinants of PD while maximally controlling for hereditary factors, 31 monozygotic twin pairs discordant for PD were interviewed by telephone. Information about possible risk factors was obtained from systematic and uniform interviews with cases and controls. The only statistically significant result was less cigarette smoking by PD patients (p less than 0.05). Thirteen dizygotic discordant twin pairs were evaluated with the same techniques, but there were no statistically significant differences between affected and unaffected twins.

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Thirteen boys and 15 girls with a history of prenatal exposure to medroxyprogesterone acetate only and 22 boys and 15 girls with exposure to a variety of progestogens and estrogens singly or in combination were studied at age 8-14 years in comparison to closely pair-matched, unexposed controls. This report concerns the findings on sex-dimorphic behavior as assessed by separate interviews with the child and his/her mother. Hormone-exposed boys and controls differed little, while in girls prenatal sex hormone treatment seemed to be associated with some degree of increased stereotypic femininity.

Career choices and their relation to personal and family background variables were studied in a sample of 148 children (68 females and 80 males) at two points in time: when the participants were between 8 and 13 years of age (Phase 1) and approximately S years later, when they were between 13 and 18 years of age (Phase 2). Male andfemale respondents during both phases chose largely nonoverlapping careers. Boys' choices were heavily gender-stereotyped during both developmental periods. In contrast over one quarter of the females during Phase 1 and close to one half during Phase 2 chose male-dominated occupations. Boys' ideal and realistic career choices did not differ in the degree to which they were gender-typed. Girls'realistic career nominations, however, included a significantly higher percentage of female incumbents in the labor force than did their ideal choices. Gender differences in career choices were not accompanied by differences in several family background and personal variables except for the desire to parent a child and pursue a full-time career.