Might seem obvious to say but we all have a mother and a father. Each has given us our DNA, but in what way? This can become a complicated answer but there have been several ways that this has been simplified over the years.
Half from Each Parent
While true you get half your DNA from mom and the other half from dad, when it comes to DNA testing this truism is applied at each marker and not each set of markers tested.
For example, your test shows that you could have given the child one of your DNA types at each marker tested and there is a 99.99% probability you are the father. You test against the unrelated neighbor kid and the test shows that you could have given the child your DNA type at 14 out of the 24 markers tested. While this is a little over 53%, you can’t be the father because you don’t share DNA types at each marker.