I can see it now ....... the genes for intelligence are finally discovered, and are modified. Thousands of babies are born with the new genes for enhanced intelligence. Unfortunately, when they enter puberty it is discovered that their sense of smell is increased by a factor of 1000. Suddenly they have a better sense of smell than dogs, but the olfactory areas of the brain is unchanged, bad smells still stink, good smells still are pleasant. Our normal sense of smell causes a whole cascade of reactions in the brain, for example, triggering memories or emotions. In our genetically enhanced kids it might lead to insanity or something as harmless as sniffing the butts of everyone they meet.
What if Eleanor Roosevelt had wings? -- Monty Python
You can't build a Time Machine without Weird Optics -- S. Valley