A story in which an old supposedly debunked theory is revived and chaos ensues. Surely you saw this coming?!

Starlight didn't, but she's actually pretty chilled out about it. As is her great-great-great-great-great-great-great-great aunt, or something like that.

Others are... less pleased.

This is based on Twilight Takes a DNA Test by Dewdrops on the Grass. All credit goes to her.