Children resemble their parents because of the genetic information they inherit from them. Every person inherits half of their DNA from each parent, which combines to form a unique genetic blueprint that determines their traits, including physical appearance.

Here’s how it works:

1. DNA Mixture: During sexual reproduction, a sperm cell from the father fertilizes an egg cell from the mother. Each sperm and egg carries 23 chromosomes – half of the full set of 46 that a typical human cell possesses. When they combine, the resulting embryo receives 23 chromosomes from the father and 23 from the mother.
2. Genes: Chromosomes are made up of genes, which are segments of DNA that code for specific traits. Physical characteristics like eye color, hair texture, facial features, height, and many other traits are determined by specific combinations of genes inherited from both parents.
3. Recombination: Before a sperm or egg is formed, a process called meiosis occurs, during which the chromosomes undergo crossing over or recombination. This means that the child doesn’t inherit exact copies of each chromosome from either parent; instead, they get a mix of maternal and paternal genetic material along each chromosome.
4. Dominance and Recessiveness: Some traits are determined by dominant and recessive genes. For instance, if one parent passes on a dominant gene for brown eyes and the other a recessive gene for blue eyes, the child will likely have brown eyes.
5. Complex Traits: More complex traits, such as facial structure, are influenced by numerous genes working together, often with environmental factors playing a role too. This polygenic inheritance explains why siblings can look alike yet different, each inheriting a unique combination of parental traits.

In summary, children look like their parents because they inherit a mix of genetic material from both parents that dictates their physical characteristics. While some traits are directly passed down, others result from a complex interplay of genetics and environmental factors, creating a distinctive appearance that reflects their genetic lineage.