Answer:
Many differences between individuals are undoubtedly because of differences in their genes. However, human monozygotic twins who are genetically identical may differ markedly from each other (Spector, 2012). Individuals differ, of course, because biological processes are inherently variable.
That people differ from each other is obvious. How and why they differ is less clear and is the subject of the study of Individual differences (IDs). Although to study individual differences seems to be to study variance, how are people different, it is also to study central tendency, how well can a person be described in terms of an overall within-person average. Indeed, perhaps the most important question of individual differences is whether people are more similar to themselves over time and across situations than they are to others, and whether the variation within a single person across time and situation is less than the variation between people. A related question is that of similarity, for people differ in their similarities to each other. Questions of whether particular groups (e.g., groupings by sex, culture, age, or ethnicity) are more similar within than between groups are also questions of individual differences.
Step-by-step explanation: