Tina Jordahl, a former Iowa State HDFS and public policy graduate student who is now a market research specialist with Hospice of Central Iowa, collaborated with Lohman on the study. 'Definitely the age is the most shocking thing about this study.' 'Those people who say that kids don't have sex at that young of age should think again,' she said. We know from our follow-up interviews that one boy who reported having sexual intercourse for the first time at age nine had fathered four children by the time he was 18.' 'A handful of kids reported having sex as early as 8 or 9. 'So if 12 years was the average age here, that meant that some kids were starting at 10 or younger,' said Lohman, an Iowa State University associate professor of human development and family studies (HDFS).