About 20 years ago I read a book that revolved around a future where genetic engineering is so commonplace that people visit genetic engineering parlors much like they do tattoo shops IRL now. At these genetic modification parlors people would have their genetic code rewritten to be more snake-like or wolf-like (so much so that they became cold-blooded or could eat raw meat, respectively) or whatever else they could think up (e.g. zombie-like or even mythical creatures such as sphinx-like). Central to the story was a genetic engineer who was a preeminent master in the field, and I forget how or why but towards the end of the novel he is killed but not before he releases a genetic modification virus planet-wide that is assumed will modify the genetic makeup of all humankind to be more kind and altruistic. I also vaguely remember another main character of the book being a female confidant to the master genetic engineer fellow.
To the best of my recollection this futuristic sci-fi story did not contain any elements of space exploration, and just occurred on Terra. Thought it was important to denote that because so much wonderful sci-fi occurs in interplanetary settings, whereas I'm pretty sure this novel just occurred on Earth.
I know it's not much to go on but I hope someone will recognize this book I'm thinking of! If any more details come to me I will be sure to post them.
As far as I know, this book was not part of a series and was a stand-alone novel. Also, I have tried but haven't had any luck searching for this novel on the interwebs...
I'm highly confident that I read this in a paperback novel form.