Sorcery is not about Black magic even though that is the common misconception. It is mostly about grey magic though I have not yet witnessed a black magic spell or even a reference of one. Sorcery is about the minipulating of the aether to cause a physical change in the materiel plane. If you need any more specific detail, look up: A sorcerer's handbook: real magic at your fingertips. to know more
I actually find it much more interesting as to why you felt the need to post this, but I digress.
Sorcery Via definition is based on "evil" spirits, but the word it self first came into use in the 13-1400's, at that time, many things were evil. The word is also acquainted with necromancy (currently used as a cover term which refers to everything from contact with the dead to actually summoning demons) which was labeled evil as people sought answers through spirits of the dead.
I will agree that not all sorcery is necessary "evil" though those (and there are some) that may dig up a person to use the bones for deviation would be labeled "evil" or mentally ill or someone like me would refer to them as something that would be inappropriate to post here.
If your talking about a physical change as in turning into a creature, I would suggest throwing the book away, however some demons are good at projecting hallucinations.
Great point but let me tell you about how I see it based ofF of the sorcerer's handbook. There have been no reference to anything evil or dealing with spirits, to further elaborate, it works on the same plane of existence as most spirits mundane or not. It works in the aether to create a physical change on the material plane. No it can not alter your genetic makeup but it definintly can allow you to cast spells with more, how should I say, physical changes taking place around your life unstead of just your or someone else's spiritual life. The aether is the "base" of our physical world, when something in the aether changes, you can be assured that the physical plane will surely catch up one way or another.