Okay, califjim already told you what i forgot to mention: it depends on what you want to contrast...
if somebody tells you "my father is a doctor" you could give him the answer "mine is a doctor, too". that´s absolutely correct. but if you just have to replace "my father" with a pronoun, the SAFEST thing would (in my opinion) be to replace it with "he".
Today Officer Buckle and Gloria came to our school. Officer Buckle is a safety officer and Gloria is a dog. Officer Buckle gave a safety talk. The safety talk was an important lesson for children. While Officer Buckle was funniest dog the students have ever seen. Don't miss their next visit!