My half sister and I share the same father, but different mothers. Because my paternity was questionable we both did an Ancestry DNA test....I matched to relatives of my grandmother and she didn't....and we didn't match to each other. I suspect we don't share the same father but she insists we do, so we uploaded our DNA to MyHeritage- and again no common matches. our father was 100% Swedish and I come up with hundreds of DNA matches from Sweden.. she comes up with 8, but her heritage comes up as having no Swedish ancestry.
Is there a scientific explanation for these results besides us not sharing a father?
I would think that these tests are accurate enough to find common DNA among half sisters or they would have been shut down due to all the grief and drama that would be caused my misinformation leading people to think their life is a lie.