The generation of characters within computer animations is currently a labor intensive and expensive activity for a wide range of businesses. Whereas prior art approaches have sought to reduce this loading by providing reference avatars, these do not fundamentally overcome the intensive steps in generating these reference avatars, and they provide limited variations. According to the invention a user is provided with a simple and intuitive mechanism to affect the weightings applied in establishing the physical characteristics of an avatar generated using an inheritance based avatar generator. The inheritance based generator allowing, for example, the user to select a first generation of four grandparents, affect the weightings in generating the second generation parents, and affect the weightings in generating the third generation off-spring avatar from these parents. Accordingly the invention provides animators with a means of rapidly generating and refining the off-spring avatar to provide the character for their animated audio-visual content.