This was the first example of a human polymorphism (other than eye colour) inherited as a single Mendelian trait.
(This; was; the first example of a human polymorphism (other than eye colour) inherited as a single Mendelian trait) (the first example of a human polymorphism (other than eye colour; inherited; as a single Mendelian trait)
This the first example of a human polymorphism (other than eye colour
was inherited
the first example of a human polymorphism (other than eye colour) inherited as a single Mendelian trait
as a single Mendelian trait