A 72-year-old man has agreed to donate his sperm to his son and daughter-in-law after the London couple were unable to conceive a child through IVF, the Evening Standard newspaper reported yesterday.

The sperm is being screened at the London Women's Clinic, where the couple, who are in their 30s and wish to remain anonymous, are being treated.

Dr Peter Bowen-Simkins, the clinic's co-medical director, told the newspaper that he had never come across a case like this before.

But advancements in fertility treatment meant that people were now willing to consider all kinds of options.

He said: "Obviously the wife's mother-in-law also had to be included in all the conversations but she has no objections. Society has also changed its perceptions of what is and what is not acceptable.

"In this case, keeping the identity of the child similar to their own was a huge factor. The husband does not have a brother, which is why he chose his own father to assist."

Any baby produced from the treatment would be the grandfather's genetic child and its father's half-brother.

A spokeswoman for the Human Fertilisation and Embryology Authority (HFEA), which regulates the fertility sector, said that it did not need to approve the decision.

Donations from family members – such as sisters giving each other their eggs – are allowed under the law, she said.