Back in 1917 when this stupid idea got taken up in Britain, while people's attentions were largely elsewhere, one of those opposed to it was Lord Balfour, who had a few years ago been Prime Minister, with a rather intriguing objection, speaking in the House of Lords:

"Supposing some unfortunate lady was confined with twins and one child was born 10 minutes before 1 o'clock. ... the time of birth of the two children would be reversed. ... Such an alteration might conceivably affect the property and titles in that House."

So you could be older than your older brother... I wonder how they have worked round that problem.