Many couples in same-sex relationships are as enthusiastic in their desire to become parents as those who are in heterosexual relationships. Adoption, surrogacy, sperm donation, have all enabled same-sex couples to achieve their parental ambitions and create families. For the most part, they have done so without any interference by, or involvement with, the biological parents after the birth of their children.Whilst the majority of lesbian parents tend to use sperm which has been obtained from an anonymous donor, some women have shown a preference to use a sperm donor who is known to them to become the biological father of their children.This may be because they want to know the background, personality and medical history of a potential father before embarking on the procreative process. In some cases, it may also be because some women want their children to have a male role model in their life. Using a known sperm donor can, however, involve risks for would-be-mothers if, contrary to the father’s wishes, they do not want him to play a significant role in the child’s life. Their dreams of creating an autonomous nuclear family may be destroyed and replaced with a new form of extended family, consisting of three or even four parents if the biological father has a partner. The tale recounted in the Appeal Court judgment in A v B and C (Lesbian co-parents: role of father) (2012) is a cautionary one for lesbian would-be-parents and one of hope for potential biological fathers who are known to them. The Court of Appeal emphasised the paramountcy of the welfare principle, contained in s1(1) of the Children Act 1989 in resolving all child contact disputes. It declined to elicit any further principles in these difficult fact specific cases and stated that the sexual orientation of the parents and their pre-conceptual agreements, or understandings, spoken or unspoken are either irrelevant (per Thorpe LJ) or relevant but not determinative (per Black LJ).* Dr Mary Welstead, CAP Fellow, Harvard Law School, Visiting Professor of Family Law, University of Buckingham. Re G; Re Z (Children: Sperm Donors: Leave to Apply for Children Act Orders)  1 FLR 1334.