A significant Court of Appeal judgment delivered last week has provided long‑awaited clarity on a fundamental question in family law:

What happens to a father’s parental responsibility when he is named on a child’s birth certificate, but later learns he is not the biological father?

In Re J, Re M and Re P [2026], the Court has confirmed that only a biological father can acquire parental responsibility through registration on a birth certificate. The ruling also outlines important guidance on how parental responsibility is gained, and crucially, how it may be lost.

This decision carries wide‑ranging implications for families, unmarried parents, and anyone involved in disputes or uncertainty surrounding paternity.

Background to the Appeals

The cases of Re J, Re M and Re P were heard together because they raised the same central issue:

Does an individual named on a child’s birth certificate automatically acquire parental responsibility, even if he is later proven not to be the biological father?

Re J

In Re J, the man named on the birth certificate had raised the child for the first two years of their life, believing himself to be the father. DNA testing later confirmed he was not biologically related to the child. Despite this, he sought to maintain his parental responsibility and continue his involvement in the child’s life.

At first instance, the High Court held that because he was not the biological father, he had never validly acquired parental responsibility, despite being registered on the birth certificate. This meant there was no parental responsibility to remove.

The matter progressed to the Court of Appeal, forming part of the conjoined appeals.

Re M

Re M involved similar circumstances, where a non‑biological father was registered on the birth certificate and believed he shared parental responsibility with the mother, having acted as the child’s psychological parent.

Re P

Re P presented a highly unusual factual background. The mother had conceived within a timeframe where she had sexual intercourse with identical twins. DNA testing was unable to determine which twin was the biological father, although only one was listed on the birth certificate. As neither twin could establish biological paternity, the question of parental responsibility became more complex.

The Court of Appeal’s Decision

On 20 March 2026, the Court of Appeal handed down its judgment, confirming:

1. Only a biological father can acquire parental responsibility through birth registration
   Registration under section 4 of the Children Act 1989 gives parental responsibility to an unmarried father only if he is the biological father.
2. Being named on a birth certificate is not enough if paternity is later disproved
   If a man is incorrectly registered as a child’s father, the registration does not create parental responsibility.
3. Social or psychological fathers do not obtain parental responsibility through registration
   Parental responsibility is tied to biological fatherhood for the purpose of section 4. Parenting roles, emotional bonds, and day‑to‑day care—while important—do not replace the legal definition of fatherhood.
4. In Re P, neither twin had parental responsibility
   As both twins had an equal chance of being the biological father and DNA testing could not distinguish between them, neither was able to demonstrate paternity, and neither held parental responsibility.

What Does This Mean in Practice?

The Court’s ruling has immediate and far‑reaching consequences for families and practitioners:

1. Birth certificates are not conclusive of parental responsibility
   A man’s name appearing on the birth certificate will no longer guarantee that he holds parental responsibility if later evidence shows he is not the biological father.
2. DNA testing will play a more prominent role
   Where paternity is uncertain or disputed, DNA evidence is likely to become essential in determining whether parental responsibility has ever been acquired.
3. Non‑biological fathers are not without options
   Although they cannot rely on birth registration alone, the Court emphasised that the family justice system must still recognise and protect important emotional and psychological relationships. Men who have acted as social fathers can seek:
   – Child Arrangements Orders (s.8 Children Act 1989), and
   – Parental Responsibility Orders (s.12 Children Act 1989)
   These allow the court to prioritise the child’s welfare, considering the reality of the relationship rather than biology alone.
4. International implications
   The decision will be particularly significant in cases involving international child arrangements or abduction, where the definition of “rights of custody” under the Hague Convention may be affected.

A Landmark Judgment for Modern Families

The decision in Re J, Re M and Re P provides vital clarity on the legal meaning of fatherhood and parental responsibility. While the ruling reinforces the importance of biological parentage within the statutory framework, it also underlines the continuing role of the family courts in protecting children’s welfare and the meaningful relationships they form—regardless of biology.

For families navigating complex questions about paternity, parenthood, and their legal rights, specialist advice remains essential.

About the author

Estella Newbold-Brown is Partner and Head of Family, advising high-net-worth clients on complex financial settlements and children matters.

Estella is a highly regarded family law specialist, advising high-net-worth individuals on complex financial and children-related matters. She acts in cases involving significant wealth, family businesses, international assets, and offshore structures, and is known for her strategic, pragmatic, and empathetic approach. She is recognised for her meticulous organisation, clear communication and forward-thinking style, ensuring clients feel supported throughout every stage of their case.