Autism is a complex developmental disorder that researchers have yet to fully understand. While genetics do play a role, recent research shows how a mother’s weight and a father’s age can also affect their child’s risk of developing autism. Previous studies have shown that as a man’s age increases, so does his chance of having a child with autism. Compared to men under 30 years old, those over 50 have twice the risk of having an autistic child. The risk increases to four times for men over 55. This finding was strengthened by recent studies that looked at genetic mutations linked to autism. These new—or de novo—mutations don’t exist in the DNA of the parents, but occur spontaneously in the egg or sperm before conception. According to one study, a particular mutation linked to autism was four times as likely to occur in fathers than in mothers. A man’s risk of having this mutation in the sperm starts to increase at age 35. Researchers suspect that this is related to the increasing number of times sperm are copied over a man’s lifetime. Mothers also play an important role in the development of the child. A study published in Pediatrics found that women who were obese during pregnancy were 70 percent more likely to have an autistic child. Likewise, women with diabetes during pregnancy had double the risk of having a child with a developmental disorder. Researchers are uncertain of the exact cause but think that fat cells may increase the amount of inflammation, which may also affect the development of the fetus’ brain. The higher levels of blood glucose seen with diabetes may have an effect, as well. They aren’t, however, ruling out the existence of another common link among the women.