They may be sexually active, but many young teenagers are not mature enough to deal with the emotional pressures a physical relationship can bring.
This week, a survey by UNICEF offered an insight into the sex lives of Irish adolescents in 2011. The report found that girls are more likely than boys to have lost their virginity by their mid-teens; 22pc of Irish girls who have lost their virginity had sex at the age of 15 or younger, with the figure for boys at 19pc.
Psychologist Allison Keating says: "For a significant minority of teenagers, often it is too much too young. There is a danger of a loss of innocence.
"We are seeing an increasing tendency for girls to go out with older boys."
There are marked regional variations in the ages when teenagers first engage in sexual activity. The UNICEF survey shows Dubliners are much more likely to have had their first encounter at a young age. Three out of 10 of Dublin teenagers who have lost their virginity did so at the age of 15 or younger.
Even at a young age drink plays a part in a teenager's first experience of sex. Four out of 10 respondents lost their virginity after drinking alcohol.
Allison Keating, who works with adolescents at the bWell clinic in Dublin, adds: "I would be concerned that girls of 12, 13, and 14 are just not emotionally capable of dealing with sex. They are being robbed of a time of their life when they should still really be children. That brings a lot of pressure that they cannot cope with.''
And the behavioural expert, who also advises troubled teenagers on TV3's Ireland AM, blames the 'Rihanna effect' for the over-sexualisation of young teenagers.
"Young girls are now encouraged to be sexually aggressive and almost act like the predators in relationships. Singers like Rihanna desensitise kids to sex as young as 11.
"There is pressure on girls to dress provocatively at a younger age, while boys are encouraged to treat them like sex objects.
"Girls believe that they should be available, but there is a lack of genuine intimacy,'' says the psychologist.
The sources used by teenagers to learn about sex make one wonder about the accuracy of the information. Parents may be ready and willing to talk about the birds and the bees, but they have been eclipsed by the internet and online pornography.
Eight of 10 teenagers said they never talked to their parents about the facts of life, and at least one of those surveyed said they were "physically disgusted'' by the idea of the subject being broached.
Fifty-seven per cent of teenagers in Ireland use the internet to find out information about sex. What is more striking is that a high number believe that they can be reliably informed by looking at pornography. Nearly 80pc of boys and 40pc of girls had watched porn, according to the report, while 21pc of teenagers said they used it to teach themselves about sex and more than one-third (36pc) believed that what they saw in pornography was accurate and educational. Although the vast majority (81pc) used contraception during their first sexual encounter, according to Allison Keating, there is still a dearth of reliable information.
"It is very much a mixed bag,'' the pyschologist says. "Some teenagers are very well versed, but with others I am horrified by the ignorance.''
One teenager, quoted in the report, said: "My parents were extremely strict, being from strict old-school backgrounds themselves, and they never once talked to me about sex until after I became pregnant -- and that was only to tell me I was stupid for getting pregnant.''
Although sex education has been mandatory in the education system for over a decade, a significant minority of schools still steer clear of the topic -- or only come to it when it is too late.
One participant in the UNICEF survey said: "(We only) had a small course on sexually transmitted diseases in sixth year. Our teacher was ancient and not in touch with the times -- very embarrassing and very awkward. It would have been better if there was someone who was more our age who had a good and healthy attitude towards sex.''
Of course it would be wrong to paint an entirely negative picture of teenage sexuality.
Recent figures from the Central Statistics Office show a significant decline in the number of teenage pregnancies -- from 3,087 in 2001 to just 2,019 last year.
While a significant minority of teenagers have sex for the first time in their early teens, the vast majority of those who were sexually active waited until they were 16 or older before they lost their virginity.
Allison Keating believes we could still do a lot more to encourage a positive attitude to sexuality, while ensuring that children do not suffer a premature loss of innocence.