What they didn't know, as she went off on a bike ride one day in May last year, was that she had made a secret pact with girls she had met in suicide chat rooms to take her own life.
Sometimes the physical changes of puberty have occurred, but a teen seems hesitant to begin dating or trying new social experiences.
The father of a 19-year-old college student shared this: "when I was his age, you couldn't keep me away from the girls.
"I think they were shocked that Carina had actually done it.
But the people behind the sites should be locked up," she said. It is horrific and the pain of losing her will never, ever go.
Pro-suicide websites and chat rooms have been implicated in the deaths of at least 16 young people in the UK in the past few years.
One of the victims was Simon Kelly, an 18-year-old with no apparent problems, or so his parents thought.
To many of these highly gifted teens, sexuality is yet another aspect of their developing self that just occurs early. I've always allowed her more freedom due to her maturity.
The mother of 16 year-old girl recently shared with me, "When she was little, asynchrony was one thing. But now, I don't know what to do."A 15 year-old boy said this, "It's hard for my parents and I right now. We didn't tell anyone; we knew no one would take us seriously because of our age. I understand, because I was only 14 or 15 at the time, but, still, I felt like they should have respected my feelings as a person."Parents' worry and confusion may not always be about very advanced development.
Under the Suicide Act 1961, assisting a suicide carries a prison sentence of up to 14 years. The Government has ruled out changing the law and seems content to leave regulation to the industry.
A spokesman for the Internet Services Providers' Association said: "It needs to be unlawful content for the industry to take action." But he added: "Suicide is something that needs to be tackled very sensitively and is something the industry is concerned about." Some internet providers, such as AOL, Google and Microsoft, now prioritise suicide charities in web searches for certain words and phrases and have chat room moderators.
For highly gifted teens in particular, physical development can add anxiety to the ongoing stress of being so different from classmates.