• Wendy Kramer set up Donor Sibling Registry online
• Half-siblings have got in contact and gone on holiday
  
• Experts worried when many live close to each other

If this sperm donor ever wanted to meet all of his children, it’s unlikely they would fit inside his living room.

He has fathered 150 children, leading to calls that cash-hungry sperm banks are allowing too many children to be conceived from one man.

The sperm donor is not identified but does have a unique number that has allowed half-siblings to get in contact with their extended family.

Cynthia Daily, 48, of Washington, used the donor to conceive in 2004 and has searched for his growing list of relatives, reported the New York Times.

She has even gone on holiday with other families in the group.

‘It’s wild when we see them all together – they all look alike,’ she told the New York Times.

Parents, donors and health experts are all worried diseases could spread faster with so many children fathered by the same man.

They have even suggested that this raises the chances of accidental incest between half-sisters and half-brothers who often live nearby.

‘She’s been in school with numerous kids who were born through donors,’ said one mother, whose teenager daughter was conceived from sperm donation.

‘She’s had crushes on boys who are donor children,’ the mother told the New York Times. ‘It’s become part of (her) sex education.’

Fertilisation: One donor has fathered 150 children, leading to calls that sperm banks are allowing too many children to be conceived from one man

Critics are concerned fertility clinics and sperm banks are making money from allowing too many children to be conceived from popular donors.

They want a limit on how many children can be conceived using the same man’s sperm – which is already in place in Britain and France.

‘We have more rules that go into place when you buy a used car than when you buy sperm,’ Debora Spar, president of Barnard College in Manhattan, told the New York Times.

Wendy Kramer is founder of the Donor Sibling Registry and had her son Ryan Kramer, 20, of Pasadena, California, through a donor.

Oscar-nominated comedy: Sperm donation was brought to the big screen in ‘The Kids Are All Right’, starring Mark Ruffalo, left, and Josh Hutcherson, right

The website helps parents to register their child’s birth. ‘They think their daughter may have a few siblings,’ she told the New York Times.

‘But then they go on our site and find out their daughter actually has 18 brothers and sisters. They’re freaked out.’

Sperm donation was brought to the big screen in ‘The Kids Are All Right’, starring Annette Bening and Julianne Moore.

In Lisa Cholodenko’s Oscar-nominated comedy film from last year, two children manage to meet their sperm donor father.