When their mother remarried in 1999, the lives of two sisters turned hellish.

Just four months after the marriage, the girls, then aged 11 and 13, were raped by their stepfather.

For nearly 10 years, he brainwashed them into having consensual sex with him and even threatened to harm their mother if they rejected his advances.

Last week, the 45-year-old man pleaded guilty to 13 charges of rape and was sentenced to 30 years' jail and 24 strokes of the cane, the maximum punishment allowed by the law.

This was not an isolated case.

There were 172 cases of reported rapes last year, up from 118 in 2006 and 129 in 2007. Statutory rape, which involves victims below the age of 14, jumped from 57 cases in 2007 to 63 last year.

From June 2006 to December 2007, the High Court heard 12 cases of serious sexual crimes including rape, attempted rape and unnatural sex.

In 10 cases, the offenders knew their victims.

Counsellors and social workers suspect many more cases go unreported.

They said that eight out of 10 sexually abused children and youth are females and their attackers are known to them. He could be a male family member, relative or family friend.

Younger children are usually targeted because they are unable to resist or verbalise their abuse to adults.

A study done by senior consultant psychiatrist Cai Yiming and consultant psychiatrist Daniel Fung of the Institute of Mental Health (IMH), which was published in 2003, showed that of the 38 sexual abuse cases the clinic assessed in 2001, 28 victims were aged nine and below.

Of the 38 perpetrators, seven were uncles, four were fathers, two were stepfathers, two were the mothers' boyfriends and one was a paternal grandfather. The others included strangers.

In a study of 80 children who had been sexually abused by family members in 2005, the Ministry of Community Development, Youth and Sports' (MCYS) psychological services unit found that about 40 per cent of them were sexually violated by a parent and another 25 per cent by a step-parent. The rest were hurt by a sibling or other relatives.

Dr Adrian Wang, a consultant psychiatrist at Gleneagles Medical Centre, said that those who rape their own children usually have an antisocial personality with little impulse control and no respect for social norms.

'They tend to be violent and impulsive and have no regard for consequences,' he said. 'To rape one's child is probably the lowest antisocial act.'

Chief medical social worker Sylvia Mun of KK Women's and Children's Hospital (KKH) said that the perpetrator's personality, sexual perversion and need to control or overpower also come into play. In addition, he could have been abused in the past himself.

Other experts added that from cases seen, the risks of sexual abuse increase when there is a stepfather in the family and when the mothers are often not at home.

IMH's study found that in most instances, the sexual abuse took place in the homes of the victims or perpetrators.

A victim's dilemma

But although these crimes happen right under their noses, family members are often unaware.

Dr Carol Balhetchet, director of youth services at the Singapore Children's Society, said that perpetrators often groom their victims by building strong bonds through bribes and favours.

'The rape is usually premeditated and when it happens, the child doesn't want to break the bond with the adult,' she said.

Consultant psychiatrist Parvathy Pathy of the IMH said that at times, young victims may not even know they have been abused.

She said: 'They don't realise it's inappropriate and wrong for their fathers to touch them in a certain way till they learn sex education in Primary5.'

Often, perpetrators also threaten to harm the victims or their mothers should they report the crime. To keep the family intact, these children keep mum.

But when children do speak up, adults may still fail them.

In the MCYS study, more than half of the family members told about the abuse failed to make reports.

Reasons vary - people could be too shocked to react or fear public shame.

Ms Mun of KKH explained: 'Sometimes mothers are afraid of the implications for the family and themselves when the abuse comes to light, like the loss of a sole breadwinner, divorce and incarceration.'

For the child, a sexual assault by a family member may be even more traumatic than if the crime had been committed by a stranger.

'It's a complete breakdown of trust as parents are meant to protect and care,' said Dr Balhetchet. 'When that trust is infiltrated, the child feels betrayed.'

The result: Victims could grow up having difficulties in trusting others and developing relationships. Some may resort to self- destructive behaviour.

'Sexually, there can two extremes - becoming promiscuous or not wanting to have sex at all, thinking that it's abhorrent,' said Dr Wang.

The Sunday Times understands that when a child sexual abuse case is reported, the police and MCYS usually step in to investigate.

At KKH, sexual abuse victims are sent by police for a medical examination. The child may need to be referred to the MCYS, especially when the perpetrator is in the family and may still have contact and access to the child.

Similarly, most sexual abuse victims seen at the IMH were referred to by the police, sometimes to assess if they are fit to give evidence in court.

At both clinics, victims are also given counselling and therapy.

Dr Parvathy, who has counselled many victims of sexual abuse for the past 15 years, said the fear of possible disruptions to family life is another reason victims are reluctant to report the abuse.

'The father may be charged, the family broken up and she may be pressured to drop the case,' she said.

Often, victims also blame themselves for allowing the abuse to occur and feel guilty for bringing shame to the family.

But Dr Parvathy emphasised: 'Not all who had been sexually abused are damaged for life. One can recover despite what happened and still make a good future.'

To bring down the number of such abuses, social workers and counsellors want more avenues created for children to report cases of abuse. Caregivers, teachers and doctors should also be more aware of signs of abuse and be more proactive in reporting cases.

Ms Mun said: 'We need to educate children that they can say no to inappropriate or uncomfortable touching, even if it comes from family members or a known family friend.'

SIGNS OF SEXUAL ABUSE IN CHILDREN

• Changes in behaviour, extreme mood swings, excessive crying, withdrawal and fear of being alone
• Sexualised behaviour like rubbing of private parts, wearing revealing clothes or using the tongue when kissing
• Regressive behaviour like clinging
• Genital injuries like bleeding and rawness

To report child abuse, contact:

• Child Protection and Welfare Helpline: 1800-258-6378 (Monday to Friday, 8.30am-5pm and Saturday, 8.30am-1pm)
• Child Protection and Welfare Services, 10th Storey MCYS Building, 512 Thomson Road, Singapore 298136
• The nearest Neighbourhood Police Post or call 999

This article was first published in The Sunday Times on Feb 1, 2009.