Meet the parents:
The concept of the broad autism phenotype sprang from landmark research by psychiatrists Susan Folstein and Michael Rutter. In 1977, they conducted the first twin study of autism, analyzing 21 sets of British twins, identical and fraternal, in which at least one sibling had the condition. They showed that autism occurs more often in both twins when the twins are identical, providing strong evidence of autism’s genetic roots. But even when only one twin has autism, the unaffected twin sometimes has delayed language and difficulties with spelling and reading. This finding led Folstein and Rutter to conclude that “autism is genetically linked with a broader range of cognitive disorders.” Folstein pursued this idea in the early 1990s, conducting some of the first studies of the parents of autistic children. Her team noticed, for example, that some parents of autistic children have mild language difficulties, recalls Landa, who worked with Folstein at the time. “Their conversational turns w...