There is a big difference between the thriller and the sf novel. As more than one person has pointed out, the thriller is generally hostile about science, the sf novel is positively tiggerish.
When Eli Samuels (a name which I think may be meant to resonate biblically—I think it was the priest Eli who brought up Samuel after his mother gave him to G-d in return for getting pregnant in the first place—one of the more bizarre bible stories), goes to work at Wyatt Transgenics his father is furious. But Eli's pretty angry because Dad has only just owned up to the fact there is is no money for college, months after it's too late for Eli to apply for scholarships. Eli is also pretty unhappy because his mother is dying of Huntington's Chorea and there is an even chance he may have it also.
Werlin does a superb job of explaining DNA, and having Eli act like a kid fascinated with science. Her mistake – from an sf point of view –is to complicate it with possible superpowers. This is really unnecessary. When Eli discovers he is the result of early gene manipulation experiments, that's enough of a shock. When he finds out that the beautiful Kayla came from an earlier egg, one his mother "paid" for him with, but one which both failed the chromosome test (ie she has HC) and also lived to be a baby when it was not expected to, he reacts with revulsion. He and Kayla destroy the laboratory and Dr. Wyatt is arrested.
All of this is written well. Eli is a convincing 18 yr old, his relationship with his girlfriend, Viv, particularly well done. But I felt at the end that Werlin coerced her reader's response.
If you read the book without the last chapter, it's all nicely ambivalent. Kayla wasn't meant to reach term, she did and Wyatt made sure she was raised. In this scenario it is Eli's mother who is the real villain being so determined not to raise an HC child. But then Werlin adds in the genetic manipulation (which is why Wyatt used Kayla's embryo and kept it alive) which starts to move him into the "nasty scientist" role. And finally we get a little bit of preaching about how awful it would be wipe out people with genetic disablements—specifically Down's Syndrome.
Now pardon me for a little bit of spleen here: but it is quite possible to have a debate here without counting all disabilities as the same, or insisting that every set of parents would make the same choice. I, for example, carry genes for a painful digestive disease. If given the chance at embryo selection I'd select a child who neither had it nor carried it. However, I wouldn't abort that embryo if it were later discovered to have the defect. Huntington's Chorea? Too damn right I'd abort. It's a vile disease. Downs? Given enough assistance, a Down's child can have a very happy life. Each and every decision is personal and can be left as personal. And finally: I refuse to accept that it matters whether I or the child my mother miscarried (thus leaving the following trimester free for me to be conceived) was born, really matters. You all wouldn't have missed me. Maybe it would be my alter-sibling you would be reading now. Or maybe s/he would be the scientist I longed to be.
This kind of book annoys me because it claims to promote free thought but right at the end closes down the ending. Note also the way that the book is brought back to the personal: Eli begins the book by moving away from the influence of father and high school sweetheart. He will end the book reviving both relationships and with the idea that external influences are dangerous and misleading. It's an odd trajectory for an sf book, one that I think has more to do with the current worry over parental influence and the idea that the well adjusted child is the one for whom the family unit is the most important element of his or her life, even when he or she enters into the workplace. It's oddly regressive for sf, if quite normal in domestic fiction.
One final point: technically this book isn't published as sf but as Puffin Sleuth. Neither Puffin nor Point now do labelled sf lines. Instead they seem to be trying to capture the sf market by the corners (Sharyn November at Firebrand books, also a branch of Penguin, is the notable exception.
[Spammers---grrrrrr.. Not sure what I can do about them. Any ideas?]