The Canadian legal system focuses on the law, and the facts. But sometimes it draws from pure science – typically to provide evidence that’s used in court. Think breathalyzer test results, or forensic evidence used in a criminal trial.
And while the use of scientific testing in Family Law is perhaps less common, it’s typically just as reliable as in any other realm.
But that’s not to say there aren’t some odd predicaments.
When DNA Doesn’t Tell the Whole Story
A recent Ontario case about child support saw a highly-unusual case where two men – identical twin brothers – were both adjudged with 99.99% certainty to be the father of a child. It seems the mother had engaged in sexual relationships with each of them over the span of a few weeks. She suspected that she knew which one was the father, but DNA tests would be needed, just to make sure.
They both took standard paternity tests, which showed something remarkable: Both brothers matched as the biological father with near-perfect certainty. This was not a lab error; since all identical twins share the same DNA, standard paternity tests cannot distinguish between them.
In other words, even science could not definitively answer the question of which of them was the true biological father.
It turns out that a specialized advanced paternity test – costing between $30,000 and $40,000 – was needed to determine which of the twins was the real biological father. Although the twin brothers were willing to undergo the testing, they balked at the cost, and wanted the mother to pay her share of the fee. The mother said she could not afford to pay – although she was willing to cooperate with any testing, and to make the child available as needed.
To resolve all this, the parties appeared before a judge of the Ontario Court of Justice (OCJ) – which is a provincial trial court covering certain Family Law matters including certain support issues. (The OCJ does not handle divorce or property issues, which are dealt with by the Ontario Superior Court of Justice).
But the OCJ judge said she simply did not have the judicial authority to force a DNA test or make a declaration about what it showed.
That’s because under the governing Ontario legislation (the Courts of Justice Act and the Children’s Law Reform Act) a judge of the OCJ was simply not empowered to determine the child’s parentage. That was the job for a different court, known as the Ontario Superior Court of Justice (or its Family Court branch).
So unless the parentage dispute could be resolved by agreement, the matter was stalled until it could be transferred to that other court for a hearing.
The Takeaway
Leaving aside the procedural hurdles, cases like this are rare — but the underlying legal issues are not.
Parentage disputes can arise in many different ways, and their resolution is not always straightforward. Questions about who is (or is not) a child’s legal parent can affect:
- Child support obligations
- Decision-making responsibility and parenting time
- Inheritance rights
- Access to benefits or government programs
What this unusual case highlights is that even when the facts seem clear – or science appears to offer an answer – legal and procedural hurdles can complicate the outcome. The choice of court, the available remedies, and the cost of obtaining key evidence can all have a real impact on how a case unfolds.
If you are facing uncertainty about parentage or your rights and obligations as a parent, experienced legal advice can help you move forward with clarity and confidence. Our Family Law team can assist – give us a call.
For the full-text of the decision, see:
M.R. v. M.W., 2025 ONCJ 107 (CanLII), <https://canlii.ca/t/k9spj>,
