father, what's your blood type?

paediatrician came by this morning to give my hospital neighbour and me the report on our new born. he announced the report to my neighbour first:

'... your baby's blood type is O. Mommy, I can see from here your blood type is B. Daddy, what is yours?'
... silence...
... silence...
'... Daddy, is yours O?'
... silence... 'urh... O...'

pppp and i couldn't help but laughed...

when it's my turn, the paediatrician was smarter. he showed me the report, pointed to the report on pp's bloodtype, and said 'this is your baby's bloodtype,'... and then pointed to my prenatal report, and said 'this is your bloodtype,'... and then he looked up and asked pppp (who was not shown the report), 'what is your bloodtype?'
and only when he found the bloodtype matched, he talked about how pppp and I contributed to pp's bloodtype...