User blog comment:Funnyman12/Wow..../@comment-30592229-20170724185900

I got the theory from PRStorm, and I found it pretty convincing. Here's what he said was evidence.

-Luan, Lynn Sr, and Mrs. Johnson all share a love of puns.

-Lynn Sr and Luan have a really strong bond, some might say more than the other sisters.

Rita's line the best 10 things that happened to US, hinting that she knows Luan isn't hers, and Lynn Sr quickly corrects her, trying to hide Luan's identity to the other Loud Kids.

-Luan and Mrs. Johnson have identical hair, aside from color, which she got from Lynn Sr.

-most comedians are mentally unstable outside od the public, her bubbly and happy personality may be a facade to hide her depression knowing she's only Half-Loud

To add to this theory.

-Mrs. Johnson said she'd be let out of her cage in "Along Came a Sister" if she typically does that than maybe once could have resulted her getting pregnant with Lynn Sr's kid.

-In "Project Loud House" Luan seemed to have no problem pranking Mrs. Johnson, something we've only see her do with people she's colse to.