"if my belly button were a knothole it would certainly be more congruous with my keg-like body. i have chiseled away at my fathers genetic code since i realized i was better equipped to roll to school than walk"
While this may make a bit more sense with context, the speaker is saying that he is a heavy-set man. The first sentence means that if he were to have an "outie" belly button, it would be more appropriate for his figure, which is round, and sturdy ("keg-like"). He then discusses how he has chipped away at his father's genes since he realized that he was destined to be significantly overweight.
