A sociologist has told the committee hearing at the House of Commons for the equal marriage bill that the idea of equal marriage, and links to parenthood, were irrelevant.

Dr Patricia Morgan told the Public Bills Committee that equal marriage had caused a decrease in marriage rates for straight people, in countries where equal marriage was already legal.

She also suggested that equal marriage was to blame for the number of children born out of wedlock, and a rise in unmarried cohabiting couples.

She submitted these claims as part of a 22 page paper submitted to the committee considering the Marriage (same sex couples) Bill, reports the Telegraph.

It contained analysis and claims based on marriage trends in Sweden, Norway, Denmark, Spain, Belgium, Canada and some US states, where equal marriage was already legal.

“From what we know about demographic trends, it is preposterous to argue that people suddenly somehow embrace marriage and slow or reverse its decline because homosexuals can have it,” Dr Morgan wrote.

“We can be certain that same sex marriage will do no such thing as encourage stable marriage whether for heterosexuals and/or homosexuals. Marriage in Scandinavia, Spain, Netherlands and elsewhere is in deep decline.”

She continued: “Same sex marriage is both an effect and a cause of the evisceration of marriage – especially the separation between this and parenthood.”

The sociologist went on to explain that equal marriage only started to become considered in countries where marriage was already in “crisis” because of a rise in the number of “out-of-wedlock births and cohabitation rates”.  She suggested that equal marriage had made such problems worse.

“If marriage is only about couple relationships, and is not intrinsically connected to parenthood, why not give the leavings to homosexuals?,” she questioned.

“As marriage is redefined to accommodate same-sex couples, this reinforces the irrelevance of marriage to parenthood,” she said.

“Elsewhere, same sex marriage is an instigator for the casualisation of heterosexual unions and separation of marriage and parenthood.”

She added: “Same sex marriage is more a terminus for marriage or ultimate act of dissolution, rather than a force for revival.”

Last year Culture Secretary Maria Miller, said that allowing churches to hold same-sex marriages would strengthen religious freedom.

Dr Morgan also claimed that those opposed to equal marriage would be victimised if they resisted against changes.

“Some clearly hope that compulsion to perform same sex weddings will sever church and state and further push Christianity out of the public arena and, therefore, consciousness,” she said.

“Undermined and stigmatised for their unreasonableness and prejudice, the moral authority of religious institutions will further retreat in favour of a narrow secular ideology, particularly as sexual behaviour at odds with traditional norms is further encouraged and advanced.”

She suggested that straight couples in countries where equal marriage was legal were 12 times more likely to separate, and that they were less stable.

She blamed on declining marriage numbers in Spain, on equal marriage being introduced in 2005 by the Socialist government there.

The first clause of the equal marriage bill has passed in the committee considering it in the UK Parliament last week.

Also last week, members of Tory leadership, including Michael Gove and David Cameron, denied that the issue of equal marriage played a role in the party losing the Eastleigh by-election, the result of which was announced today.