User blog comment:The Shadow User/Solana Vakarian/@comment-730941-20101016010518/@comment-730941-20101016085521

An interesting question. Again, we could assume that Garrus never mentions his father because it just didn't come up in conversation.

But I think you may be right about some sort of falling out between Garrus and his father. From the first game we know that the father was very by-the-books in terms of adherence to regulations and a refusal to go beyond the law to fight crime. Perhaps Garrus' vigilante efforts upset him, or maybe Garrus didn't even tell his father what he was doing. We saw from his intercepted conversation with Solana that he was being secretive about his activities, even to his own family. I don't think Garrus' father will come up again much anyway. There are quite a few characters we heard about in the first game that appear to be solely for background (Ashley's sisters, Kaidan's friend Rana, etc).

Also just out of curiosity, I've never heard Solana given a gender. Are we assuming they are female? It's a little hard tell from the conversation.