When do we grow up? I've met many adults over the years who have yet to show signs of maturity, and some grow more childish with every candle they add to their birthday cakes.
But in a legal setting, these are difficult questions.
The decision to class the sixth gangrape accused as a juvenile, because it excludes the possibility of the death penalty, may look like an example of what some call "soft-touch justice".
Different countries have different approaches. In the US, the legal drinking age is 21; in parts of Canada, 19, and in the UK, 18. The age of consent for sexual relationships is 16 in many countries, but some argue it should be lowered to 14, recognising the younger ages at which people become sexually active.
There are plenty of cases of people having sex below the age of 14. Does that mean they know what they're doing? They might have the knowledge - ie "this is sex" - but not the maturity to perhaps understand potential consequences, the meaning or lack thereof, and the difference sometimes between sex and intimacy.
Similarly, at what age does a young person understand what he or she is doing criminally? That's not an excuse for committing a crime, but it is a circumstance that is as relevant as if a person had a mental health problem or was under the influence of an addictive substance. These elements are part of the "why" behind crime.
Many countries allow for someone under the age of 18 or indeed 16, to be tried as an adult, despite clearly being under the age at which we normally determine adulthood. This allows a measure of flexibility when a youth matures faster than others might, frequently through the circumstances of his or her surroundings. A child forced into exploitation or slavery might have the maturity to survive like an adult, but would we still treat that victim as an adult?
Having been recently catching up on the seminal TV series The Wire, there are countless child characters in that programme who act as adults and commit worse crimes than adults, adding to the shock of the show. But it adds to the very real question of how to treat them in the criminal justice system. They are clearly children; their crimes are anything but innocent in nature.
Did this sixth individual in the gang rape act as an adult or a child? We don't know. But the severity of the crime doesn't remove the necessity of asking the question.
The Justice Verma Report rejected lowering the age of the Juvenile Justice (care and protection) Act, 2000 to 16. Keeping the cut-off generally makes sense, but there may be a need for more flexibility, allowing someone under 18 but perhaps over 14, to be tried as an adult.
Yet even if you send a younger person to an adult court system, they should still be sent to a different punishment facility if found guilty than an adult. They can be transferred to adult facilities once attaining a certain age, but otherwise you risk sending a child into an adult world, potentially subject to worse treatment or exploitation than an adult put into such a setting.
And even if you are in favour of the death penalty and even if the crime is unspeakably heinous, would you still be willing to argue for the state to execute someone under the age of 18? At what age is it too young to be killed as punishment?
Justice Verma's recommendations should be adopted as sensible reform. But we can still debate how best to prosecute, punish and rehabilitate those under the age of 18. It is not a sign of weakness in society to acknowledge that young people can be different from adults.
If the system for youths can be abused, that is a separate issue to the particular case of those involved in the gang rape in December. Don't confuse the horrors of one crime for the criminal potential of young people, or their measure of guilt.
There can be a flexibility to justice depending on circumstances, the accused, and the evidence. The more rigid a criminal justice system, the greater the opportunity for miscarriages of justice and for punishments that don't fit the crime. Recognising the subtleties of justice is a sign of maturity, whatever the age of those passing through the system.