The short answer

It is common and it is normal. The American Academy of Pediatrics states that behaviours which may look sexual "are common in children, especially between about 3 to 6 years old", and that "usually, they are a normal part of development."

It also explains what is actually driving it: "at a very young age, children begin to explore their bodies. They may touch, poke, pull or rub their body parts, including their genitals. It is important to keep in mind that these behaviors are not sexually motivated. They typically are driven by curiosity and attempts at self-soothing."

Self-soothing is the key word for toddlers. Much of the touching happens when a child is tired, bored, anxious or watching television — the same moments that produce thumb sucking, hair twiddling or ear rubbing in other children.

What counts as common

The AAP lists the behaviours it describes as normative and common in 2- to 6-year-olds:

touching or rubbing their own genitals, in public or private;
looking at or touching a peer's or sibling's genitals;
showing their genitals to peers;
standing or sitting too close to someone;
trying to see peers or adults undressed.

It also gives a general test that is more useful than any list: common behaviours "are transient, not very frequent and can be easily diverted."

One specific worry deserves a direct answer. The AAP addresses it head on: "caregivers often assume that self-stimulatory behavior such as masturbation must have been taught, suggesting that the child was sexually abused. This is not the case. Children simply find their genitals, recognize that stimulating them feels good and continue to engage in the behavior."

How to respond

The AAP's guidance is short: "in general, a young child's sexual behaviors that are easily redirected and do not cause harm or distress are not a cause for concern. When these behaviors happen, it is important to stay calm and not become angry or upset. Instead, try to redirect your child's attention."

It even supplies the wording: "It's OK for you to touch your own body but you should do that in a private place."

That sentence does a lot of work. It does not tell a child their body is shameful, it does not create a secret, and it gives them a rule they can follow. Say it once, quietly, and then change the activity — a toddler with occupied hands is not a toddler with a hand down their trousers.

Do not shame or punish. Reacting with disgust attaches shame to a body part, which is the outcome nobody wants, and the NHS's general behaviour advice is that attention given to a behaviour tends to increase it.
Do not make it a big conversation. Brief and matter-of-fact works better than an explanation a toddler cannot follow.
Name the private places. Bedroom and bathroom are the usual ones.
Redirect rather than forbid. Hand them something. Change the room. Start a different game.
Brief the other adults. The NHS advises that everyone close to a child deals with behaviour in the same way, which matters here because an inconsistent reaction from one grandparent can undo a lot of calm.

Teaching body words and boundaries

This is the age when the useful groundwork gets laid. The AAP advises teaching children the proper names for body parts, warning that "making up names for body parts may give the idea that there is something bad or secret about those parts." It also says to teach which body parts are private and "shouldn't be looked at or touched without their permission", including the parts covered by a swimming costume as well as the mouth, and that a child must ask and receive a spoken yes before touching someone else.

It goes further, on body autonomy: children "should not be forced into physical contact with anyone, regardless of their relationship", and adults should recognise and support a child who is uncomfortable with hugs and kisses, offering waves or high-fives instead. It suggests modelling this by asking your own child whether you can give them a hug or kiss, and respecting the answer without making them feel guilty.

Check for a physical cause

Persistent touching, scratching or fiddling — especially at night, or with visible redness or soreness — may not be self-soothing at all. Threadworms are the most common culprit: the NHS describes them as causing "extreme itching around the anus or vagina, particularly at night", along with irritability and waking during the night. A pharmacist can help with that.

Other physical causes worth considering are nappy rash, thrush, soreness from bubble bath or soap, eczema, and irritation from tight clothing. A urine infection can also cause discomfort. If the touching seems driven by discomfort rather than comfort, see a GP or pharmacist rather than treating it as behaviour.

When to seek advice

The AAP describes a spectrum, and the far end is not what this page is about. It flags as uncommon in typically developing children behaviours such as asking a peer or adult to take part in a specific sexual act, inserting objects into genitals, explicit imitation of sexual intercourse, and any sexual behaviour involving children four or more years apart in age. It also flags behaviours that persist and are resistant to being redirected, that happen very frequently or daily, that cause emotional distress or physical pain, that involve coercion, or that occur alongside physically aggressive behaviour.

If you see any of that, or if something simply does not sit right with you, speak to a GP or health visitor. The NHS advises talking to a health visitor or GP if you are seriously concerned about your child's behaviour, and the HSE encourages asking for advice if behaviour continues and you feel lost. Raising it is not an accusation and it is not an overreaction; it is a conversation with someone who has had it before.

Toddler Touching Their Private Parts: Is It Normal?