Vivid memory

Okay so, I have this vivid memory that is nagging me. I was probably about 5 and my younger sister was probably about 3. My mother called us over to her and when we were standing in the kitchen my mother all of the sudden was nice to us (she was extremely abusive that is why this was weird behavior from her she was never this nice) out of nowhere she said “okay girls we are going to do a strep throat test” as she was opening up some at home kits (we were not sick at all). She swabbed our cheeks, not the back of our throats. she was telling us she was going to send it to the lab and just being weird. With all of the other crap going on in my life I just didn’t think about this for a bunch of years. well my mother died several years back now and we started piecing everything together and realized she had multiple affairs (some of the people she was sleeping with (while married to my dad) were bragging about having sex with her to me and my younger sister after she died yeah I know.. real classy...) I remembered this and I asked my dad and my older half sister randomly “is a strep throat test the one where you swab the back of the throat?” Both of them said yes so I told them about this memory and my older half sister said yeah that was a DNA test not strep. My father and I talked about this further and we ended up saying even if we weren’t his he would still be our dad.

I am just curious and I am not sure if I should do one of these DNA tests myself just to see but at the same time idk if I want to go down that rabbit hole..... what are your opinions?