The Girl on the Train - by Paula Hawkins

I read this book quite quickly and, ultimately, enjoyed it. Clearly I am not alone, as I observe that it is the #1 selling Kindle book in the UK at the moment. The story was easy to read, but complex enough to keep me interested, employing 3 viewpoints and 2 timelines. I have to say that the characters are quite clearly depicted, but I did not like any of them. That is OK - I do not have to like the people to enjoy a book. What concerned me was that the main female characters are all rather self-obsessed and the males are testosterone-driven thugs. What does this say about the author and her background?