Single women and lesbian couples will be able to seek fertility treatment without having to consider a father for their children under new laws approved by MPs last night.
Attempts by the former Tory leader, Iain Duncan Smith, to insist that clinics take account of a child's need for a father and mother when deciding on treatment were roundly rejected in a free vote that cut across traditional party lines.
The Commons voted by 292 to 217, a majority of 75, to throw out the cross-party amendment, despite claims that it was "common sense" to involve both sexes in children's upbringing.
Under the new Human Fertilisation and Embryology Bill, women seeking fertility treatment will no longer have to take into account the role of a father figure. Instead, the rules will be replaced with references to "supportive parenting".
MPs also threw out a Conservative attempt to insist on "a father or male role model" when clinics help women to conceive.
In an impassioned debate yesterday members of all parties cast aside usual political loyalties to clash over questions of discrimination, parenthood and the very nature of family life.
Iain Duncan Smith, told MPs that children who grew up without a father were more likely to fail at school or have problems with drugs and alcohol. He said: "We are saying come on, this is common sense. All we are saying is 'Take consideration of the need of a child for a father' not 'If you don't have a father you will never get treatment'. It's only considering it."
Geraldine Smith, Labour MP for Morecambe and Lunesdale, said: "To most people outside this House you are just talking common sense. They would wonder why we are even having this debate.
"Is there any wonder people think politicians are out of touch with ordinary people when we have debates such as this. It's nonsense to suggest that we shouldn't take into account the need for a father."
But her Labour colleague Emily Thornberry, the MP for Islington South and Finsbury, warned: "I always worry when people start saying they are only applying common sense, because so often common sense is a cover for discrimination, narrowness and an inability to face the 21st-century."
The veteran Conservative MP, Sir Patrick Cormack, said: "Whatever may be the case in Islington, in Staffordshire it's thought normal for a child to have a mother and a father. Do you think it is as normal for a child to have two mothers?"
Tory Mark Simmonds said: "It is important to send through this particular piece of legislation a message to the country that fathers are important in the welfare of the child."
His party's amendments were: "about retaining a male influence in a child's upbringing, providing a balanced outlook to society, " he said.