I know this is not the answer you want to hear, but they are all correct! No matter how to change around the words, you are making it very clear that right now in the present time you have two parents who are doctors. You have discovered 4 different ways to say the same thing. I am a native speaker and any one of these sentences can be said and understood in any situation. I hope this helped. Good luck with your studies. Feel free to ask for help any time.

All of your sentences are correct. Your sentences are all correct. All your sentences are correct. As you can see, there are a number of ways to express this same information. Your third sentence is rather awkward, but the others are commonly used.

1 and 2 are correct. 4 would be fine in spoken, informal English. It would be problematic in written or formal contexts. 3 would be understood, but it sounds a bit funny.