Genetics professionals have been reluctant to test children for adult-onset conditions because they believe this would create psychosocial harm to children not counterbalanced by significant benefits. An additional concern they express is that such testing would violate the autonomy of these children as adults. Yet weighing the harms and benefits of such testing results in a draw, with no substantial harms proven. Moreover, such testing can enhance, rather than violate the adult autonomy of these children. In deciding whether to proceed with predictive testing of children, parents, mature children, and health care professionals should consider a complex of factors relevant to the particular child. The importance of these factors will vary depending on the condition at issue, the age and stage of development of the child, family dynamics, and the concerns, values, and objectives of the parents and mature child. The final decision whether to test a child for an adult-onset condition should rest with the parents and the mature child.