( ( Two genes ) ( each ( ( have ( two alleles ) ) . ) ) )
(ROOT (S (NP (CD Two) (NNS genes)) (DT each) (VP (VBP have) (NP (CD two) (NNS alleles))) (. .)))
Two genes each have two alleles.
(ROOT (S (NP (NP (DT The) (NN majority)) (PP (IN of) (NP (JJ human) (NNS genes)))) (VP (VBP have) (NP (QP (CD two) (CC or) (JJR more)) (JJ possible) (NNS alleles))) (. .)))