printed on the bottom

All kids of the colony used to play together in the evening after school.few were elder to us(me and my cousin) A dog had given birth to few pups and we all used to play around it. A little elder boy in the group told us 4 male pups and 3 female.I had seen him lifting the pups to see.I went back home after the day's play and announced Jacky had given birth to puppies and that 4 were male and 3 were female, to everyone. My surprised granny asked me how do you know? I replied I think its printed on the bottom ( I had some time back over heard dad asking his friend to check the bottom of a bottle for the price and tell him ),my cousin who was with me blurted out,I think we need to check the bottoms to reconfirm too ! Both our mom's were embarrassed to the core but then our granny( mother in law of our mom's)smiled at our mom's.Am not sure if my cousin remember's this incident !If she does would have loved her inputs as well