If you could go backwards, prenatal existence rarely makes the cut of a time you're likely to want to revisit. After all, that's before you existed, so you would either be interacting with your mom, or you'd be on another plane existence, a cellular level, inside of a placenta or a needle. For me, the scar could have been the needle, since my mom aborted one of us at eleven weeks and I was born at twenty four, a miracle of modern medicine that I've since made it to twenty four years rather than weeks, avoiding death regularly outside of that womb rather than narrowly avoiding death within it. My birthmarks weren't birthmarks, but scars of the battles fought in infancy.

But other people’s could easily be scars from the battles fought before conception, prior lives even. There's a midrash that states all babies know everything there is to know until an angel pinches them under the nose right before birth to make their mind empty again, so for all of our lives, we never actually anything for the first time, we're always re-learning what we knew before birth. That mark between our nose and mouth then is the scar of the angel’s pinch, so perhaps other birthmarks are scars from angels doing other acts of violence against our unborn bodies, ones we may have even consented to before knowledge of consent was removed alongside everything else in our minds.