User blog comment:AustinDR/Not a Loud (My Prediction)/@comment-31563773-20170814062415

Austin, why did you even bring this up? There's plenty of evidence that shows that Lincoln wasn't adopted:

He has freckles like a few of his sisters

He has a rare condition where his hair lacks pigmentation, called poliosis (which dispelled any other rumors as to why his hair is White and the main reason people think he's adopted)

Sports a cowlick like Lola

Shares a common middle name with a few of his siblings

In his baby photo he looks similar to Lucy and Lily

And that's just the basis of his physical appearances and relation to his sisters. I haven't even gotten into the personality aspects.