A 12-year-old girl rushed to hospital with stomach pains gave birth to her brother's baby, a court heard.
The girl was 11 when she was raped by her 14-year-old brother in their family home, Swansea Crown Court heard.
The court heard the siblings had grown up in a "dysfunctional" household with "blurred sexual boundaries" and a culture of "secrecy and lies".
While prosecutors said there were no suggestions that any coercion or threats had been involved in the incident, the teenage father - who is now 16 and cannot be identified for legal reasons - had previously pleaded guilty to two counts of statutory rape.
His barrister argued that a custodial sentence would "achieve little but cost a great deal" and the teen, who is now living with foster parents, was handed a two-year youth referral order with a supervision requirement and an activity requirement. He will be a registered sex offender for 30 months.
The court heard that the offending came to light when the girl was rushed to hospital in Carmarthenshire in the early hours of the morning suffering with severe stomach pains. She had given birth within a couple of hours.
The court heard that when a midwife asked the girl whether she had had sex, the youngster replied that she didn't know. When asked if she had consented she said she thought so but wasn't sure.
Georgina Buckley, prosecuting, said it was not clear whether the girl realised she was pregnant or not. She told a midwife she had not known but was overheard telling other people in hospital that she had.
When the girl's teenage brother was interviewed by police, he admitted that he and his sibling had been "wrestling" downstairs on one occasion while their parents were out and had then gone upstairs to wrestle on the bed as it was more comfortable. He said they had begun kissing before each removing their own clothes and then having sex.
The prosecutor said there were no suggestions that any coercion or threats had been involved in the incident.
In an impact statement read to court the girl said she didn't want to go home any more and just wanted to live the normal life of a girl her age and wanted her baby to have the best life.
Dean Pulling, representing the defendant, said it was clear from numerous reports that the children had been subjected to a "dysfunctional, neglectful, and potentially abusive upbringing" where there was little in the way of parental control or guidance and there were "blurred sexual boundaries".
The barrister said the defendant had been routinely exposed to pornography in the family home from the age of 10 and the children's mother and father created a culture of "secrecy and lies".
He said: "Children are the products of their upbringing and the environment they are exposed to."
The court heard the defendant is now living with foster parents, is responding well to their positive influence, and is remorseful.
Watch the latest videos from Yahoo News UK