HOW DO WE KNOW WHETHER TWO GENES ARE LINKED? A B X a b ● B b B a or B B Parental Non-Parental AB Ditype Ab Ditype AB (PD) Ab (NPD) a b a B a b a BHOW DO WE KNOW WHETHER TWO GENES ARE LINKED ? X a b A B A A a a B B b b A B A B a b a b B B b A b A a a or A b A b a B a B Parental Ditype (PD) Non-Parental Ditype (NPD)