Because Mrs Knight's doctor disapproved - she was already a grandmother to her daughter's three children - the family sought help from the controversial charity Childlessness Overcome Through Surrogacy.
DIY insemination Mrs Moore, who says the surrogacy was her idea, became pregnant using a DIY insemination kit provided by the charity.
A woman has given birth to her own stepbrother after acting as a surrogate for her mother, it emerged yesterday.
Carole Moore, 29, decided to have the baby for 52-year-old Maureen Knight after womb cancer robbed Mrs Knight of the chance to give birth.
The baby, called Luke, was conceived using the sperm of Mrs Moore's 57-year-old stepfather Harry, Mrs Knight's third husband.
So Luke is both Mrs Moore's son and her stepbrother.
Mrs Knight is raising Luke alone in a flat in Bournemouth after her amicable split with Mr Knight, a retired Merchant Navy engineer, who lives in nearby Poole.
Mrs Moore, a nursery nurse, refers to Luke as her 'brother'.
Her three grown-up children by her 39-year-old husband Mark, an Army warrant officer, look on the boy as their uncle - although he is their half-brother.
But he is being raised as a son by Mrs Knight, who has since broken up with her husband.
Moral implications Last night, the surrogacy - which is thought to be unprecedented - provoked an outcry over its ethical and moral implications.