It's not easy being a teenage girl in this modern world, a rapidly evolving cultural global village where there are few constants and fewer rules. But if it's difficult for the child, it can also be bewildering for the parent, too, especially those experiencing this phase of rearing for the first time.
And often they don't know where to turn, where to draw the line, when to say 'no' and when to give a tentative 'yes'.
Allison Keating believes the rate of change has been nothing short of extraordinary.
The Dublin-based psychologist says teenagers' relationship with sex has changed utterly in just five or six years.
"It's all down to social media and technological advances," she says. "What's happening is that teens are being exposed to a coarsened version of sexuality on sites like Ask.fm, and they are now able to access pornography 24/7 on their smartphones or tablets.
"That has altered their perception of what sex is and has skewed their expectations as well. You have a scenario where some young girls are behaving in a stereotypically male, laddish way by seeking out casual sexual encounters and having numerous sexual partners. You have young boys who feel that sex should be like the stuff they see online. It's a real worry."
Keating is especially concerned about the risky behaviour of very young teens. "They may have the biological maturation to have sex," she says, "but they don't have the neurological, emotional maturation for it."
Her concerns are well-founded. As well as seeing more clients who are sexually active at adolescence, an extensive survey by Unicef Ireland shows that of those teens who say they have had sexual intercourse, 3pc lost their virginity at 13 years of age, while 7pc lost theirs at 14.
Where once "first base" referred to kissing, Keating believes that today it more accurately describes fellatio – something that was brought into sharp relief last month when explicit photos of a 17-year-old schoolgirl performing a sex act on a teenage boy at a rock concert were widely disseminated on social media.
"That's the other thing that really complicates the picture: there's a big risk now that misdemeanours will end up online, thanks to some bystander with a camera-phone. There are also genuine concerns around the awful phenomenon of 'slut-shaming' where, typically, other girls name acquaintances who they believe have been sexually active.
"I'm not for a moment suggesting that all teen girls are acting this way – of course they're not, most navigate these years absolutely fine – but there is much greater pressure to be sexually active today than at any time before."
It is a sentiment shared by psychologist Deborah Mulvany, whose RTÉ documentary on the subject, Generation Sex, offered something of an eye-opener for blinkered parents when screened earlier this year.
"I wanted to portray teens' views on sex as accurately and as non-sensationally as possible," she says. "Some parents were taken aback by it – especially the fact that their child may be consuming a lot of pornography online – but it is always best to have open discussions about such things and not sweep them under the carpet.
"What's clear is the teen sexual experience today is shaped in ways that their parents simply couldn't have envisaged. The best way to understand your child is to talk to them. Don't assume that someone else will."
"It's sad to see pre-teen girls wearing skimpy, revealing clothing, and it is little wonder that when they become a teenager, their choice of clothes gets more and more provocative. In an ideal world, they should be able to wear whatever they want, but the parent needs to sit down with them and tell them why wearing very short skirts and high heels can send out the wrong message – and potentially lead to very serious problems."
She contends that the drink-to-get-drunk culture among some teens only serves to exacerbate high-risk behaviour. "They may understand the importance of safe sex, but that can go out the window if they're inebriated. The tragedy is that some of these girls may pick up sexually transmitted diseases that lie in their bodies undetected until they are in their 20s and 30s and want to have children."
O'Callaghan has two daughters – aged 23 and 29 – and says the teen years of their generation "seem very innocent" compared to what 13- to 19-year-olds have to contend with now.