“We seem to have not got rid of titles, but I think since we have them, I would like to see them gender-blind,” said the bill’s sponsor in the House of Lords, Lord Lucas of Crudwell and Dingwall, who because of a historical quirk is one of the few hereditary peers whose titles can pass to girls as well as boys.

The House of Commons sponsor, Mary Macleod, a Conservative, pointed out that of 92 hereditary peers in the House of Lords, just two are women. “It only affects a few people, but it’s symbolic,” she said of the proposal. “It’s saying that right now, do we think that men and women are equal?”

The current rules have created all manner of family trouble.

“When we were growing up, it was always, ‘When your brother lives here. ...’ ” said an aristocratic woman who grew up on a grand estate she loved, only to have her younger brother inherit it when their father died. The woman, who spoke on the condition of anonymity because she did not want to stir up family grievances, said that no one ever questioned the system.

“Even though my father had witnessed his mother’s near-collapse at not inheriting the house she grew up in, he did not adjust his own behavior towards his daughter,” said the woman, now in her late 50s. “Though I loved him and he loved me, the rule of inheritance was as strong for him as the rule that you do not have children out of wedlock.”

She is lucky: her brother lets her and her children visit the house whenever they want. Some sisters are not so fortunate. The children of the late Lord Lambton, for instance, have been locked in a nasty dispute over his multimillion-pound estate, which when he died in 2006 passed down entirely to his youngest child and only son, Ned.

Three of his five daughters have sued their brother, claiming that since Lord Lambton spent his last decades in his villa in Italy, his estate should be subject to Italian law, which does not have primogeniture. They are asking for $1.5 million apiece. The brother — whose arrival in the family, a much-wanted son after five daughters, was celebrated with an ox-roasting and a bonfire — has countersued in English court.

Citing the legal battles, the sisters did not want to comment. But Peregrine Worsthorne, a prominent writer and political commentator who is married to Lucinda Lambton, one of the daughters, said that the system had wreaked havoc on the family.