Heredity and Evolution – Introduction
Girl 1: Meet my twin. She is my carbon copy
Girl 2: No I am not. She is my carbon copy
Girl 1: Anyway its awesome to have a twin. Someone who can share your secrets with. Twins speak their own language. Did you know that? What sounds like baby’s babbling could actually be cryptophasia, a language developed between twins that they can only understand.
Girl 2: how does this happen? Are all the twins the same? And if they are same, how exactly same are they? I have no clue. She is the biology expert. So you are going to get all the answers from her.
Girl 1: twins are formed when two offsprings are produced by the same pregnancy and then, you have two types of twins. Twins can either be monozygotic, means they are formed from one zygot that splits and forms two embryos. So the first kind of twins will be the identical twins, one that look exactly the same. And the second type of twins is called the fraternal twins. Now, there are many sub-types, depending on whether the placentas are shared or not, whether it’s a boy-boy, boy-girl or girl-girl combination, what is the degree of separation involved and so on. And now, lets stick to the main categories when the same sperms fertilizes the embryo that divides, you get identical twins and if I present you identical twins and ask you, how can you tell me who is who? What would you say? What are the differences and how did these differences actually come about? Now, identical twins are exactly the same and we call this external appearance the phenotype and they are set to be phenotypally the same and since the DNA are same too they are set to have the same genotype. Gene for genotype, and their genes are the same. But are identical twins phonotypically the same for life? Is it absolute necessary? A very big question and I am going to give you some time to think about it. And when we get back, we will be equipped with a lot of information which will help you understand this confusing question and many more such questions in just a few seconds.