A complex interaction of genetics and environmental factors are responsible for making you who you are today. Organisms are able to pass their genetic traits to their offspring. This is why you share many of the same characteristics as other members in your family.
Gregor Mendel, the "Father of Genetics," was the first scientist to mathematically show through his experiments with pea plants that organisms inherit traits from their parents. Over time, other scientists noticed that some patterns of inheritance follow the dominant and recessive pattern described by Mendel, while some patterns are more involved. For some traits, the internal or external environment plays a part in their expression. While genetics determines your physical traits, it can also pass along genes responsible for genetic disorders.