I'm disappointed. Mostly because, while the writing isn't bad, the author's understanding of viruses leaves much to be desired. 
 I am expected to believe that a viral 'cloud' of unknown origin hovers in space, that the virus remains active and viable for over 70,000 years, in vacuum, without a host, and at one point created a bottleneck in humanity's genepool. Also that, while modern humans are immune due to past exposure, modern mice are not. 
 Not even touching the concept of our super-advanced alien cousins and their apparantly idyllic society. 
 No. Just no. That's not how that works. 
 Two things I liked. 
 1. Middle-aged mother protagonist 
 2. Focus on family relationships and identity throughout the book