Twin children were videotaped hitting an inflated clown figure. Three behaviors (number of hits, intensity of hits, and number of quadrants hit) showed adequate response characteristics, rater reliability, and test-retest reliability. Twin analyses of the three behavioral ratings yielded no evidence of hereditary influence. (Author)

This final report reviews the second phase of a life-span study of boys with fragile X syndrome (FSX), the most common known inherited cause of mental retardation. Males with the syndrome are more severely affected than females and in males, delays are usually evident in all the developmental domains, although cognitive and communication skills…

Examined evidence for reciprocal influence between adoptive parents' behavior and heritable characteristics of adopted children. Found that psychiatric disorders of biological parents were significantly related to children's antisocial/hostile behaviors and consequently with adoptive parents' behavior. Also, the adoptee's antisocial/hostile…