How does an iPhone decide on whether it should send a text to Messages or Android SMS?

I have an android phone and a Macbook for work, I set up Messages on my Mac with my email account so that I could join group chats with my family. Now when they try to text me individually it all goes to my Mac and not my phone. I'd like to be able to receive all texts on my phone but still be able to join in on group chats via my mac. But how?