It seems that the point which parent post wanted to make with "your DNA is not really yours" is that matching your DNA does not really need your DNA, as the DNA

It seems that the point which parent post wanted to make with "your DNA is not really yours" is that matching your DNA does not really need your DNA, as the DNA of your relatives (e.g. that aunt which opted-in to some genetic testing) is sufficient - your DNA isn't really yours because all your blood relatives share big parts of it, so their consent to use their DNA effectively provides most of your DNA as well.