There’s lots going on in the lives of four-year-old boys, including how to regulate their emotions. Let’s not blame their hormones. from www.shutterstock.com October 23, 2017 Health Check: do boys really have a testosterone spurt at age four? Kate Steinbeck, University of Sydney Some parents think their four-year-old boy's emotional outbursts and aggressive behaviour can be blamed on their hormones. Here's why that's a myth.