User blog:The Shadow User/Solana Vakarian

After completing Lair of the Shadow Broker, one of the files on Garrus had a conversation between him and a Solana Vakarian, and from the way they spoke to each other it sounded as though they were, related like brother and sister (Correct me if im wrong) and that his mother waxs ill, but no mention of his father. Now my only question is, why wouldnt Garrus have ever mentioned he had a sister, or that his mother wasnt doing well? And where is his father now? Any ideas?