 So today's topic is about theories of growth. So there are various theories of growth of head and face region in orthodontics. The theories are genetic theory, sutural theory, cartilage theory and functional matrix theory. One of the first theory is genetic theory. So it was given by Alan G. Brody in 1950s. According to this theory, the growth is controlled by genes. As the name suggests, the control of growth is on genes. So it is more of an assumed theory than a proven one. There is no proof for this theory. It is more of an assumption. So according to this theory, head and face grew from growth centers. So we know growth centers. So the head and face grows from growth centers. The point is under strict genetic control. So there is a strict genetic control upon the growth of head and face. So primarily, genetic control determines the initial features. Later, the second truly, the local feedback and inner communication happens between cells and tissues. That is a process of growth. Primarily, the genetic control determines the basic initial features, then the local feedback and inner communication. That is a further growth. That is happening between cells and tissues. So this theory is not accepted at all because this theory can't explain the role of epigenetic and environmental factors. So this theory is later replaced by many theory. This is one of the first theory because of this genes involvement. A part of this was correct, but it cannot prove or it cannot explain the entire growth of head and face region because it is not considering the epigenetic and environmental factors of growth, which has significant roles in the growth and development of head and face. Because genetics control only certain features, no complete influence on the head and face region. Suppose if genetic theory is true, we could predict the future of a children from the ciflogram of parents. If this is to be true, we can easily predict what happens or what would happen for children from the ciflograms of parents. But this is not at all possible. To an extent, we can say that this might happen, but there is no complete assurance that this would happen because there is always involvement of epigenetic and other environmental factors and other growth factors. But there is a slight favoring side, the significance of development of malocclusion because mostly the occlusion similarities we can see which runs in families. Malocclusion will be of little significance under genetic theory. So genetic theories, most of the things are against genetic theory. So only few things like malocclusion, some similarities which can be caused by the genetics. Genetics is there definitely. Genetics has a role, but we cannot explain the entire growth of head and face by the genetic theory. So a part of genetic theory can be accepted, but not completely. So this is the first theory that is genetic theory given by Alan G. Brody, complete control of genes. Primary it has initial control on basic features and there is cells and tissues, inner communication and local feedback. There is no emphasizing on epigenetic and environmental factors. So it rejected a little influence on the malocclusion because there is occlusion similarities in the family. So now let's move on to the future of theory.