A MOUSE without a father has been created for the first time in an experiment that shatters the standard scientific belief that mammals of the same sex cannot produce viable offspring.

Kaguya, which takes her name from a Japanese fairytale, was conceived from the unfertilised eggs of two mothers, making her the first mammal to be born without a male genetic contribution.

While experts said that the technique would never be suitable for human use because of the complex genetic engineering it involves, the breakthrough in Japan offers the strongest evidence yet that it might one day be possible for homosexual couples to have their own genetic children.

Before Kaguya’s birth, scientists had generally thought this impossible because of a phenomenon known as “imprinting” that requires mammalian embryos to have a male and female input to develop normally. The achievement at the Tokyo University of Agriculture has shed important new light on the workings of imprinting, with implications for fertility treatment, livestock breeding and therapeutic cloning.

Mammals are the only group of animals that do not sometimes reproduce by parthenogenesis, a process in which unfertilised eggs start to develop on their own and produce healthy offspring. Aphids and turkeys are among the species that employ it, and some lizards breed exclusively in this way.

Tomohiro Kono, leader of the Tokyo team, whose findings are published today in the journal Nature, claimed Kaguya as the first example of a mammal born by parthenogenesis. This, however, has been challenged as she has two parents rather than one, and did not develop from a single unfertilised egg.

What is beyond dispute is that she is the first mammal to be born without a father. Even female clones such as Dolly the sheep technically have a father — the male that sired the female adult from which they were cloned.

Times Recommends

• Sarah Brown says 'no thanks' to veal at G8 - twice
• Stockton-on-Tees is obesity capital of Britain
• Stores blame poor sales on Murray factor