Motor development of autistic monozygotic twins: a case study.

A pair of autistic monozygotic twins were assessed on relevant portions of the Geddes Psychomotor Inventory. Over-all motor development of the 3-yr., 6-mo. old twins was similar and considered a partial consequence of the same genotype and comparable environmental experiences from birth. The twins exhibited poor or unsuccessful performance on tasks requiring abilities in language, communication, and appropriate relationships to objects; superior performance on specific fine manual motor skills, walking balance board, and climbing; at-age performance on tasks which were considered measures of patterned gross movement, balance, postural maintenance, and spatial orientation; and few typical autistic motor characteristics.