Their children might have brown eyes or blue eyes--or the genes might combine to produce a new trait, such as hazel eyes.
(Their children; might have; brown eyes or blue eyes) (the genes; might combine; to produce a new trait, such as hazel eyes) (the genes; to produce; a new trait, such as hazel eyes)
Their children the genes the genes
might have might combine to produce
brown eyes or blue eyes
to produce a new trait, such as hazel eyes
a new trait, such as hazel eyes