I'm surprised you didn't learn this in school. I've found a chart that might help you.
http://www.disabled-world.com/calculators-charts/blood-chart.php
My "father" is type O. My sister is A+ and I'm AB. Can an AB child have an O father? My parents are deceased. What test(s) are available to determine if we are full siblings?
If you reallywant ot go all out, you can get a DNA test.
