Bart’s controversial origin story claimed that his lack of intelligence was hereditary, but Homer has seemingly forgotten this fact in The Simpsons season 33. Although Bart is nowhere near as bumbling as Homer in The Simpsons, he’s also not as unusually intelligent as his sister Lisa. The Simpsons once provided an in-universe explanation for this disparity, although Homer has seemingly since forgotten about this explanation.
In “Lisa The Simpson,” (season 9, episode 17), Lisa fears she is genetically predisposed to a lack of intelligence because she shares Homer’s Simpson genes. However, by the end of the episode, she is reassured that those genes only affect male Simpsons, something that briefly dismays Bart before he almost immediately stops caring. This fits with the devil-may-care attitude that leaves Bart in detention writing lines on The Simpsons' opening credits chalkboard, but the explanation was still somehow forgotten by Homer in The Simpsons season 33.
In “Marge the Meanie” (season 33, episode 20), Homer fears that Marge’s secret propensity for pranks means Bart doesn’t have any obvious genetic connection to him. This completely ignores the earlier episode’s revelations, which Homer not only understood at the time, but also explained to a dismayed Bart. However, there might be an explanation for this that doesn’t involve The Simpsons retconning the earlier episode’s plot, which otherwise would seem to be the case. Homer may have not remembered the fact that Bart is a Simpson through and through precisely because the "Simpson gene" has made him immediately forget this information - and thus, Homer’s failure to recall the existence of the Simpson gene is actually deeply in-character for him.
Although The Simpsons season 33 retcons include a serious number of story details, the idea that Homer would forget Bart’s proven genetic connection to him is one change that does make sense according to Homer's character. However, this still reinforces the deeply questionable depiction of intelligence seen in the earlier episode. Although the genetic predilection toward lacking intelligence that is depicted in “Lisa The Simpson” is clearly not intended to be taken seriously by viewers, claims that intelligence is hereditary have nonetheless been rife in controversial pseudo-science for decades. Thus, while it would be somewhat unreasonable to blame The Simpsons outing for perpetuating the misconception as it is intentionally outlandish, the idea that a parent’s intelligence genetically defines their child’s potential intelligence is still unfortunately prevalent.
That said, The Simpsons has never taken itself seriously enough for this to become a full-blown controversy. Much like other cartoon comedies like South Park, which The Simpsons season 33 has copied, Matt Groening's long-running comedy takes a sardonic, ironic approach to every subject, meaning the far-fetched depictions of hereditary intelligence seen in “Lisa The Simpson” can’t be given much weight by even the most credulous viewer. This makes it all the more fitting that the show’s hero himself, Homer, appears to have completely forgotten all about the "Simpson gene" by season 33. The character detail is further evidence that The Simpsons is still more than happy to potentially undo its canon for the sake of a gag or a subplot.