Blood type fortune telling _ blood type fortune telling method

A and B are dominant and O is invisible (when O and A or B are together, only the characters of A or B are displayed).

Generally speaking, everyone is determined by two blood types, one is from parents.

There is only one possibility for people with type O blood: OO (total invisibility).

There is another possibility for people with AB blood: AB (full exposure).

There are two possibilities for type a people: AA AO.

There are two possibilities for type B people, BB BO.

Father A+ mother A= child a, o

Father A+ mother B= children A, B, AB, O.

Father A+ mother AB= children a, b, AB

Father A+ mother O= child a, o

Father B+ mother A= children A, B, AB, O.

Father B+ mother B= child b, o

Father B+ mother AB= children a, b, AB

Father B+ mother O= child b, o

Father AB+ mother A= children a, b, AB

Father AB+ mother B= children a, b, AB

Father AB+ mother AB= children a, b, AB.

Father AB+ mother O= children a, b

Father O+ mother A= child a, o

Father O+ mother B= child b, o

Father O+ mother AB= children a, b

Father O+ mother O= child o