a. Dizygotic twins originate from two different eggs, whereas monozygotic twins come the same egg. Monozygotic twins are"identical" because they come from the same egg, and so similar traits between them do not indicate any hereditary tendencies. Dizygotic twins come from two different eggs. Because of this, similarity between them is more likely to be due to a hereditary tendency, because both eggs had to individually inherit the trait.
