correct me if im wrong

let the allele for cleverness be C
let the allele for dumbness be D
co-dominance takes place

so clever ppl (special stream) : CC
(vice-versa)

when a clever person mates with a stupid person,
the end result will all be normal intelligence kids

when a clever person mates with a normal person,
then end result will be
clever:normal
1 : 1

when a normal + normal
end result will be
clever:normal:stupid
1:2:1

when stupid + stupid
ALL will be stupid
(and vice-versa for clever also)

in the world, i think case 2 takes place more than the other cases,

and of course continuous variation will take place, meaning normal may rise to clever or drop to stupid:)

make sense??????