Are all children of same parents the same blood type?

of course they can, it doesnt mean that if you dont have the same blood type as your siblings, your adopted or something. if your parent's blood types differ from each other there is a huge tendency that the sibling's blood types are different from each other. for exaple your father is a heterozygous A while your mother is a heterozygous B.. their children's blood types can be AB, and an O can also be one of the possiblities.. if its too complicated to understand then you can just learn it from your genetic lessons in Biology..