When victim's are asked about their perpetrators' age, things get hairy.
Thordis Elva, Chair of NORDREF, went live on air at the National Broadcasting Service of Iceland (RÚV) to discuss the characteristics of perpetrators in cases of online abuse against women and girls, as described by their victims. The research revealed that a majority of sexual harassment in the form of unsolicited nude photos (also known as dick-pics) is perpetrated by men unknown to the victim. Other forms of online abuse were also researched in NORDREF's study, including threats and image-based sexual abuse (also known as "revenge porn".) Victims were asked about the perpetrator's gender, relationship to them and age - which in the case of strangers had to be, well, guesswork.
Listen to the interview here (in Icelandic), starting at 48:30.