Bad habits worry parents. We see our 4-year-old sucking his thumb and imagine him as an 8-year-old, getting teased by classmates. We see our 10-year-old biting her nails and have visions of her first interviewer noting down the habit with distaste.

But what we think of as bad habits often start out as innocuous childhood habits, curiosity, or even as developmental milestones. When they linger, we dub them ‘bad’ in an effort to help our children mature. But at what point is the crossover? At what age do our expectations of proper behaviour match their abilities?

We spoke with child and family therapist Shamin Mehrotra, of Ummeed Child Development Center in Mumbai, to find out.

Sucking a thumb

Kids come wired to suck – in the first stages of life, it’s how they eat, and they often come to associate the action with comfort. Thumb sucking is actually a soothing mechanism, one that helps a child learn to self-regulate their hunger, anxiety or sleepiness.

Some children never suck their thumbs, and others grow out of it early. Most children grow out of this habit by around age 4, or when they enter school and experience peer pressure.

But some children may take a little longer, and Mehrotra advises parents not to compare. By around age 5 or 6, permanent teeth begin to sprout, at which point passively resting a thumb in the mouth is OK, but vigorous thumb sucking could damage to the teeth and jaw.

At this point, she suggests parents observe what is triggering the habit. Is something nearby causing him anxiety? Does she get hungry half an hour before dinnertime? Is he trying to stay awake to catch the end of his favourite cartoon show? In other words — what is she gaining out of sucking her thumb?

If the habit continues beyond age 6 or 7, parents can talk to the child about socially appropriate behaviour and provide positive reinforcement when the child isn’t sucking his or her thumb, Mehrotra says, but under no circumstances should parents resort to ridicule to break the habit.

Biting nails

Much like thumb sucking, nail biting is a soothing habit that can start early. Unlike prolonged thumb sucking, however, it’s not really harmful unless a child bites his nails hard enough to become sore or bleed. (In fact, recent research suggests the exposure to the extra germs could be beneficial.)

The cut-off age for this is less developmental and more dependent on parent’s social perceptions, given that nail-biting can continue well into the teenage years and adulthood. Most families begin actively discouraging the habit at around 7 or 8, Mehrotra says.

Before pulling the hand out of your child’s mouth, she adds, it is better to try to figure out why she’s biting her nails. Triggers can be mitigated and parents can help make the child aware when she is doing it and offer distractions.

Avoid punishments, Mehrotra says, and only use unpleasant-tasting ointments or sprays if the child is on board with curbing the habit that way.

Not washing hands, brushing teeth, etc.

There are always pains in getting children to the point where not only are they physically capable of good personal hygiene, but they are also able to shoulder the daily responsibility.

Mehrotra says by 4 to 5 years, most children are physically able to brush their teeth and wash hands on their own – but cognitively, they may not fully grasp why it’s important, which could keep them from owning the routine.

The only way to navigate this transitional gray area is with patience. Explaining why handwashing is important – repeatedly – is better than scolding.

Not bathing

Like with handwashing and toothbrushing, children may be physically capable of bathing themselves before they’ve developed the cognitive maturity to appreciate the need for doing it thoroughly; during this transition, many parents are plagued with  half-scrubbed hair, knees and ear.

Patience, as well as trial-and-error, is really the only way to put your kid on the path to being responsible for his hygiene. While some experts say at age 6 children should be bathing themselves (with a parent nearby), others put the mark closer to age 8 or 9.

Regardless, kids move at their own pace, and you could be checking behind ears for another couple of years. If you’re looking to speed up the process, Mehrotra suggests reading a children’s book about good hygiene with your child.

Eating things other than food

As babies, children often explore by putting things in their mouths. But by roughly age 5, Mehrotra says, kids should have been able to wean themselves of the habit, called pica.

Beyond that age, she notes, eating non-food objects can be a cry for attention or a manifestation of anxiety, so as with nail biting and thumbsucking, parents should watch for the trigger. At the same time, pica can lead to food poisoning and constipation, so parents should speak with the child about the potential consequences without resorting to threats and unscientific explanations.

If this doesn’t help, see your GP or your child’s pediatrician.

Touching private parts in public

This is a particularly fine developmental line to walk without getting or causing embarrassment. Up until around ages 4 or 5 years, it could simply mean the child needs to go to the loo. But by around age 9, kids may be unknowingly getting some pleasure out of touching themselves as a precursor to masturbation.

Kids develop a sense of public versus private early in childhood. At around age 2, when teaching kids about good and bad touches, parents can also teach them that touching their own bodies is a private matter.

Losing belongings

Few parents find every bit of stationery intact in their child’s pencil box. Until what age is it a kid just being a kid and when is it irresponsibility?

Mehrotra says that by age 6 or 7, children can be expected to take responsibility of their belongings, particularly if the good habit is inculcated from an early age by, say, labeling things.

But if your kid is still misplacing things right and left, Mehrotra says involving her in a fun search for it is a better response than scolding or simply replacing the pencil with a new one.