The Hotel Valdivia is one of the more unusual institutions in the Chilean capital, Santiago. Even when you are standing almost outside it, there's little indication of the forty exotic rooms inside: everything from a bedroom modelled on a Moroccan palace to one based on an African hut.

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The Valdivia is one of hundreds of 'love motels' found throughout Chile: and they're a wonderful metaphor for the Chilean approach to sex.

The 'love motels' are havens for those conducting illicit affairs, and for the thousands of young couples still living with their parents who are desperate for privacy. Yet while it may be couples who go in, it's always been seen as the woman's sole responsibility to care for the fruits of these encounters.

Today more than half of all children in Chile are born outside marriage, and until now men were free to simply abandon their girlfriends, leaving them literally holding the baby.

That was until the end of last year, when Congress passed an inheritance law which requires fathers to recognise their so-called 'illegitimate' children. Thousands of women are now preparing to take their former partners to court to prove their paternity. Lidia Casas is one the lawyers helping them to bring their cases.

Presenter Bob Howard interviews lawyer Lidia Casas: her office has been swamped with paternity cases

"There was a lot of social stigma associated with being born out of marriage", she says. "Children were refused entrance to certain schools and their birth certificates were stamped with the word illegitimate." The paternity legislation is also meant to bring an end to this sort of discrimination. In the last few months alone, more than a million Chileans have applied for new birth certificates which make no mention of the circumstances of their birth.

I met with Ana Farias, one of Lidia's clients and heard how a paternity case unfolds. Ana's former partner attended the birth of their daughter Nicole, but has refused to recognize her as his daughter, and left Ana to bring her up entirely on her own. He's been summoned to attend a family court, but Ana's not even confident he'll turn up.

Fernando, like Ana's former partner, is one of thousands of men being forced to confront what he's finding a very unpalatable truth. He's a respectable university administrator who had a son seventeen years ago as a result of what he calls a 'fling'. He's never recognized his child and now has a wife and two other children.

He's just received notification that his former partner has decided to take him to court unless he accepts his responsibilities. "It may sound very hard but that child was not a wanted child", he says. " I did not want to have any children."

Director Jorge Rodriguez and Chief Scientist Hugo Jorqueira, at the Servicio Medico Legal's DNA-testing suite

The women's secret weapon is DNA testing, the crucial linchpin in the paternity law. The Servicio Medico Legal in Santiago now proudly boasts three brand new DNA testing machines, in what they claim is the most hi-tech centre in Latin America. Under the law, men who dispute their paternity are obliged to take a test. Refusal is considered tantamount to admitting you're the father.

It's this chance to present overwhelming evidence of paternity before the courts that's inspiring women across the country to challenge the fathers of their children. So far, the centre has processed more than two thousand samples and expects to face an even greater flood of cases as the year progresses.

Iglesia Hermana de la Providencia, Santiago: the Church is still one of Chile's most influential institutions

The paternity law is likely to have wider repercussions throughout Chilean society. "It is an absolute social revolution" says Hernan Montealegre, a human rights lawyer who's also representing paternity case clients. At present there is no legal divorce at all in Chile, but opinion polls show an overwhelming majority of Chileans favour a law to make it possible.

There's no doubt, however, that the government would face huge opposition from the Catholic Church - which along with the army represents the country's most formidable institutions. "The church will hold true to the values which it considers sacred", says Father Fernandez, the Church's spokesman on the family. "We will defend life, marriage and the family."

The Presidential Palace, La Moneda, is now open to the public: a symbol of new attitudes in Chile?

Despite the Church's protests, members of the new government are adamant that change is coming. "Society is different. What has not changed is the letter of the law", says Marie Antoinetta Saa, who helped pilot the paternity law through congress. "I think our laws will eventually reflect the way we live today."

In the meantime, children like seventeen-year-old Natalya are caught in the middle. Abandoned by her father, her disabled mother was left alone to bring her up. They're now suing him for financial support. But Natalya is determined not to face the same circumstances as her mother. She's training to be a mechanic so as to be self-supporting. "If I have the bad luck to meet a man who leaves me to look after the kids, I want to be financially independent" she says.

Also in this edition of Crossing Continents: a passionate debate between two students over how Chile can face up to the legacy of torture and repression from the Pinochet era; and a visit to the Chinchorro mummies - relics of a civilisation older than Ancient Egypt.