Can paternity be determined by identical blood types?

Question

If you have the same blood type, for example if both blood types are O, can that determine paternity without a DNA test?

Answer 1

No.  A simple blood test can return one of two results:  

1) It could prove that the man can't possibly be the father

or

2) it shows that the man might be the father.

Answer 2

Not really.

If the baby is AB and both parents are O, the baby is probably not theirs, but it needs to be proven.

Answer 3

Not positively, no.

If blood samples of the child and potential father are taken, there are certain combination types which are NOT biologically possible. This would not confirm positive paternity (i.e., it would not prove that he IS the father), but it could confirm negative paternity (i.e., it could prove that he is NOT the father).

Answer 4

No it cannot.  Blood types are controlled by a different set of factors within DNA.  It is possible for parents to have a completely different blood type than their child, hence why it is impossible to use blood type as a means of genetic identification.

Hope this helps.