Why do we not look exactly like our parents?
Traits and characteristics of parents such as eye color, skin tone, height, etc., are passed on to the offspring in the form of genes. The genes are transferred from both parents and not only from one parent. This passing down of the traits from parents to offspring or from one generation to the other is called heredity.
The passing of the genetic factor can be either through asexual reproduction or through sexual reproduction.
Sexually reproducing organisms receive half of their inheritance patterns, or genetic information, from either parent; this explains why offspring from sexually reproducing organisms are not exactly identical replicas of their parents, but may resemble them closely.
Each human cell contains 23 pairs of chromosomes except sex cells. But when they combine (Sex cell and egg), they form a total of 46. Chromosomes are strands of DNA in the nuclei of cells that carry genetic information in form of genes. Meiosis produces gametes (egg and sperm cells). During meiosis, genetic information is exchanged between inherited copies of a chromosome pair of both parents to produce new combinations of genes.
We are not exactly like our parents due to meiosis because during meiosis crossing-over occur between homologous chromosomes that results in genetic variation. Independent assortment is also the reason because one pair of homologous chromosomes separates into gametes and each gamete independently assorted into different combinations of chromosomes that results in genetic variation.
On the other hand, asexually reproducing organisms give all of the genetic information of a single parent by the process of mitosis, which is cell division. This, then, explains why asexually reproducing organisms are exact genetic replicas of their parent.