Using new statistical tools, Kathryn Roeder has led an international team of researchers to discover that most of the genetic risk for autism comes from versions of genes that are common in the population rather than from rare variants or spontaneous glitches.

Published in "Nature Genetics," the study found that about 52 percent of autism was traced to common genes and rarely inherited variations, with spontaneous mutations contributing a modest 2.6 percent of the total risk. The largest study of its kind to date, the team also showed that inheritability outweighs environmental risk.

"From this study, we can see that genetics plays a major role in the development of autism compared to environmental risk factors, making autism more like height than we thought - many small risk factors add up, each pushing a person further out on the spectrum," said Roeder, professor of statistics and computational biology.

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Mindfulness meditation has become an increasingly popular way for people to improve their mental and physical health, yet most research supporting its benefits has focused on lengthy, weeks-long training programs.

New CMU research is the first to show that brief mindfulness meditation practice - 25 minutes for three consecutive days - alleviates psychological stress.

"More and more people report using meditation practices for stress reduction, but we know very little about how much you need to do for stress reduction and health benefits," said lead author J. David Creswell, associate professor of psychology.

Premiering at 9 p.m. EDT, Wednesday, July 30, the episode will show Ferguson - who thought that he came from a "nice, normal family" - uncovering the life of his great-grandfather whom trouble seemed to follow at every turn.

"Jesse's ancestor had an unusually varied career that included a lot of ambiguous episodes, which is the kind of history that is the most fun to investigate and learn about," Sandage said.