The study follows a landmark Government-backed report on the sexualisation and commercialisation of childhood by Reg Bailey, the chief executive of Mothers' Union last year which raised concerns that children are being pressurised to grow up too fast.
His report prompted retailers to promise to stop selling "sexy" underwear to children and Ofcom, the broadcast regulator, to pledge to tighten up its use of the watershed.
But the Family Lives report warns that the previous emphasis on girls could be obscuring dangerous new trends among boys, with an emphasis on violence against other children.
It follows evidence to MPs last week by Sue Berelowitz, the Deputy Children's Commissioner, about a gang rape of a young girl by boys aged 14 and 15 who were summoned to take part using Blackberry messages.
"There is a great lack of accurate and up-to-date information on the prevalence of youth sexual violence, especially upon younger age groups; hence it is easy to simply dismiss the issue as extremely rare," the report warns.
"However, from our work … we know that this is a growing problem and as more cases of early sexual violence appear and throw light on the problem of peer-on-peer abuse, it is important to highlight this seldom discussed problem and work towards measures to tackle it."
The report highlights accounts from parents including a father who was horrified to discover his 11-year-old daughter had been having sexually explicit exchanges with a 14-year-old boy online.
"From what I can tell she has showed him parts of her body on a webcam and possibly sent him photos of herself," he said.
"I was extremely shocked to find this out as she has shown no interest in boys/sex/kissing etc.
"But reading through the message history that I have found she has been discussing sex with him. She has also accessed porn sites."
A mother also described how she discovered her teenage son had been involved in what she said amounted to "cyber-sex".
The report found that only a third of parents have spoken to their children about pornography and even fewer had tackled issues such as "sexting" - sending sexually explicit images by text.
Claire Walker, head of policy at the charity, said: "The scale of this is just not clear.
"The Government needs to commission some pretty solid research that looks at what is the extent.
"We know that hypermasculinity seems to be on the increase and one of the traits of it is peer-on-peer violence but all the evidence about hypermasculinity at the moment comes from America.
"Some of the things that we are aware of going on such as sexting and digital abuse - this is not just in urban schools or in state schools it is everywhere.
"Teachers don't always know how to deal with it and parents, on the whole, probably don't know it is going on."