As investigators try to unravel the possible motives of the Boston marathon bombing suspects, factors like their Muslim faith and family histories are being dissected. But their age and gender are perhaps so obvious, we don’t consider them as factors. "I'm currently at a child development conference and here, if you'd gone up to anybody, even before they knew a single thing [about the suspects] and asked them who did this? They'd all say: Male in his 20s," said Laurence Steinberg, professor of psychology at Temple University.