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Incest can be defined as sexual activity with a person from within the immediate family. However, the exact relationships which can be construed as incest will vary from culture to culture. Many countries have laws that forbid incest but there is considerable variation in the exact nature of these.

In England and Wales the Sexual Offences Act 2003 created an offence of familial sexual abuse (this is covered in Scotland in the 2009 Sexual Offences Act, and in Northern Ireland in the Sexual Offences Order 2008). The aim of this law was to protect children up to the age of 18 from any form of activity that a person would consider sexual or indecent. The offender may be an adult or another child. It recognises the modern family unit and it defines familial sexual abuse as being between a person and their parent (including adoptive or foster), grandparent, child, grandchild, sibling or half-sibling, uncle, aunt, nephew or niece[1].

The Sexual Offences Act 2003 also prohibits adult sexual relationships but within a slightly narrower definition that includes just close blood relationships only - parent, grandparent, child, grandchild, brother, sister, half-brother, half-sister, uncle, aunt, nephew or niece.

The most common manifestations are sibling incest and father-daughter incest[2].


Sibling sexual abuse is usually recognised as being the most common form of sexual abuse within families. It has been documented as being five times more common than father/stepfather abuse[2]. Father-daughter incest was reported by 2.5% of female participants in an anonymous computer-assisted self interview[3]. One study from Scandinavia looked at all child sexual abuse in one area[4]:

  • Girls were victims in 85% of the cases, boys in 12% and boys as well as girls in 3%.
  • Sexual penetration had occurred in 53.7% of cases and there was genital or other physical manipulation in 29.6%.
  • In 16.7% cases there was no physical contact but there was some kind of non-contact molestation or exhibitionism.
  • Most perpetrators (72%) were well known to the child.
  • The most severe violations (regarded as the ones where there was sexual penetration) were significantly more often committed by biological relatives, household members, or family friends than by strangers.

See the separate Safeguarding Children - How to Recognise Abuse or a Child at Risk article.

The offender is reported as male in most cases but female involvement may be under-reported. Although sibling incest is thought to be the most frequently occurring form of incest, the abuse of daughters by fathers or stepfathers is more commonly reported[5]. Abuse by stepfathers is up to five times higher than that by biological fathers. Physical symptoms may include:

  • Vaginal pain
  • Rectal pain
  • Vaginal discharge
  • Bleeding
  • Chronic dysuria
  • Bedwetting
  • Constipation

Incest is usually repeated and will often continue for many years. As the daughter reaches an age when she may be able to resist or flee, the activity may be repeated with a younger sister. Though the profiles of incestuous families may vary, the father-perpetrator is typically an immature individual with low self-esteem, while the wife-mother is depressed, helpless or otherwise emotionally absent[6]. The father often uses alcohol to allay his inhibitions before molesting his daughters. Theories have proposed that girls may feel powerless to take active steps to end the abuse for fear of disrupting the family unit[7].

Psychological symptoms include:

  • Deliberate self-harm.
  • Nightmares.
  • Sleep disorders.
  • Aggressive behaviour.
  • Withdrawal.
  • Post-traumatic stress disorder.
  • Poor concentration.
  • Poor performance at school.
  • Depression.
  • Phobias.
  • Eating disorders.
  • Precocious sexual behaviour with peers.

The increase in the divorce rates may have placed more children at risk than previously. When women begin new relationships, they may unwittingly be putting their children at greater risk for sexual abuse from the men they date. The study by Stroebel et al identified risk factors for father-daughter incest[3]. In the study, father figures were included within the definition of father-daughter. These risk factors included:

  • Parents where the relationship involved verbal or physical fighting increased the risk of father-daughter incest five-fold.
  • Families where father-daughter nudity was accepted increased the risk.
  • Homes with a single-parent mother or where divorce/death of the father resulted in another man living at home, tripled the risk.
  • Maternal affection was protective - but the likelihood of being a victim of father-daughter incest was highest if a girl's mother never kissed or hugged her.

According to another survey, if the mother remarries, "the stepdaughters are over eight times more at risk of sexual abuse by the stepfathers who reared them than are daughters reared by their biological fathers"[8].

See the separate Safeguarding Children - Referral and Management of an Abused or At-risk Child article for details as the principles of management are the same.

  • The child's welfare is paramount. The child's best interests override other considerations such as confidentiality, consent and the carer's interests.
  • Where there is an immediate risk of serious harm to a child, act immediately.
  • Share information with other agencies on a "need to know" basis.
  • Where possible, and if compatible with the child's best interests:
    • Respect the child's views.
    • Obtain consent.
    • Involve the carers (if the child is competent, this must be with the child's agreement). Do not involve carers if this would compromise the child's safety or evidence.
  • Keep full and contemporaneous records.
  • Remember other children in the household - are they at risk?
  • All doctors have a duty to safeguard children and to ensure follow-on care for the child:
    • The non-specialist's role is not to make a definite diagnosis of child abuse but to recognise the possibility and enlist appropriate help.
    • The doctor concerned about a child must ensure follow-on care.

Further reading and references

  1. Sexual Offences Act 2003

  2. Krienert JL, Walsh JA; Sibling sexual abuse: an empirical analysis of offender, victim, and event characteristics in National Incident-Based Reporting System (NIBRS) data, 2000-2007. J Child Sex Abus. 2011 Jul-Aug20(4):353-72. doi: 10.1080/10538712.2011.588190.

  3. Stroebel SS, Kuo SY, O'Keefe SL, et al; Risk Factors for Father-Daughter Incest: Data From an Anonymous Computerized Survey. Sex Abuse. 2013 Jan 29.

  4. Carlstedt A, Forsman A, Soderstrom H; Sexual child abuse in a defined Swedish area 1993-97: a population-based survey. Arch Sex Behav. 2001 Oct30(5):483-93.

  5. Cyr M, Wright J, McDuff P, et al; Intrafamilial sexual abuse: brother-sister incest does not differ from father-daughter and stepfather-stepdaughter incest. Child Abuse Negl. 2002 Sep26(9):957-73.

  6. Kutz I; Revisiting the lot of the first incestuous family: the biblical origins of shifting the blame on to female family members. BMJ. 2005 Dec 24331(7531):1507-8.

  7. Herman JL; Father-daughter incest, Boston. Harvard University Press, 2000.

  8. Russell DEH; The secret trauma. Incest in the lives of girls and women. Rev Ed, New York: Basic Books, 1999

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