It may seem like a silly idea to collect a DNA sample from mom for a DNA Paternity Test because there’s no doubt she’s mom, right? However, her DNA contains valuable information that can help strengthen the results of your paternity test or other tests to establish grandparent or sibling relationships.
Think of it this way: Both mom and dad give the child half of the child’s DNA. So if we test mom we can determine which half she contributed and which half came from dad.
In some rare cases, having the mother’s information along with the dad’s can mean the difference between an inconclusive DNA test result and a conclusive one. This is why we say her sample is highly recommended but not required. Most DNA paternity tests can be done conclusively without the mother’s samples.