If only the key to the door marked a decisive transition into adulthood… In reality, the 18th or the 21st is not really a milestone in development, but a cursory nod in that direction.

For many parents, their supposedly grown-up children are still in advanced states of dependency (possibly even encouraged to be so by doting parents), living at home, subsisting on parental allowances, childishly confident that they are not responsible for a range of mundane concerns (laundry, tidying room, procuring and preparing food, clearing up afterwards). That landmark birthday can feel a very long way from reality, and the prospect of the fledgling flying the nest can still seem impossibly distant.

Growing up is not a decisive series of landmarks, but rather a process of attrition. As you pass your driving test, leave school, gain the right to vote, go to university, take your first holiday abroad without your parents etc. the bonds that tie you to home and family begin to fray. The final cutting of the ties can be expedited by many things (relationships, rows, ambitions), or delayed by laziness or over-protective parents.

Ultimately, children do become adults, just as other stages in development – sleeping through the night, potty training, relinquishing the comfort blanket – seem impossible dreams at the time, but eventually are achieved and forgotten.

So enjoy the 18th or 21st birthday for what it is – a symbolic celebration. Maybe the real growing up will not adhere to the rules of the calendar, but it will come eventually…

How to Celebrate an 18th or 21st

As a parent you may well have to face the fact that your son or daughter wants to spend their 18th or 21st well away from parental supervision. This is only natural, and probably the best you can do is facilitate their plans (either through financial subsidy or help with the organisation). They can have a great time away from their parents’ eagle eyes – an inevitable sign that they’re growing up.

But if all they want is to throw a party for their friends, you will probably find yourself deeply involved. They may well still live with you and, even if they are away at university or living elsewhere, may still regard the family home as their personal property.

In an ideal world, you should organise the party in another venue (hotel, bar, club etc.), but in reality this is an expensive option, which not everyone can afford. If you do feel obliged to offer your home, take some simple precautions:

• If at all possible, make the garden the focus of activities (bad news for those with winter birthdays).

• Remove all valuable or breakable items, roll back carpets, or cover them with old rugs or carpet offcuts. Drape light-coloured upholstery with throws (or even sheets).

• Keep certain rooms (e.g. your bedroom or study) off-limits. Put a No Entry sign on the door, and lock it if at all possible. If you can’t lock the door, drag a heavy item of furniture in front of it –- it will at least act as a disincentive.

• Supply the drink, or at least supervise the purchasing of it. Stick to wine and beer – no spirits, and no lethal fruit punches (these innocuous-tasting concoctions are often formidably strong, with predictable results…).

• Provide plenty of stodgy food – bread, rice and pasta salads, or baked potatoes are all ideal ways of soaking up the alcohol.

• Impose a curfew – i.e. an agreed time when the music stops and the guests depart. Then warn the neighbours…

• If you’ve got the nerve, go out for at least part of the evening; no self-respecting party host is going to appreciate the spectre of their anxious parents in the background. But don’t stray far from home; you’ll need to be on hand if there’s an emergency or a dispute with neig