The way in which traits are passed from one generation to the next-and sometimes skip generations-was first explained by Gregor Mendel. By experimenting with pea plant breeding, Mendel developed three principles of inheritance that described the transmission of genetic traits, before anyone knew genes existed.
http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593
By extrapolating from his earlier data, Mendel also predicted that the inheritance of one characteristic did not affect the inheritance of a different characteristic. Mendel tested this idea of trait independence with more complex crosses.
http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593
Heredity is the passing of phenotypic traits from parents to their offspring, either through asexual reproduction or sexual reproduction. This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism.
https://en.wikipedia.org/wiki/Heredity
Heredity of phenotypic traits: Father and son with prominent ears and crowns. DNA structure. Bases are in the centre, surrounded by phosphate–sugar chains in a double helix. In humans, eye color is an example of an inherited characteristic: an individual might inherit the brown-eye trait from one of the parents. Inherited traits are controlled by genes and the complete set of genes within an organism's genome is called its genotype. The complete set of observable traits of the structure and behavior of an organism is called its phenotype. These traits arise from the interaction of its genotype with the environment.
https://en.wikipedia.org/wiki/Heredity
Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits. He recognized the mathematical patterns of inheritance from one generation to the next.
http://www.dnaftb.org/1/bio.html
Our modern understanding of how traits may be inherited through generations comes from the principles proposed by Gregor Mendel in 1865. However, Mendel didn't discover these foundational principles of inheritance by studying human beings, but rather by studying Pisum sativum, or the common pea plant.
http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593
3) The Law of Dominance: An organism with alternate forms of a gene will express the form that is dominant. The genetic experiments Mendel did with pea plants took him eight years (1856-1863) and he published his results in 1865. During this time, Mendel grew over 10,000 pea plants, keeping track of progeny number and type. Mendel's work and his Laws of Inheritance were not appreciated in his time.
http://www.dnaftb.org/1/bio.html
In fact, the three principles of inheritance that Mendel laid out have had far greater impact than his original data from pea plant manipulations. To this day, scientists use Mendel's principles to explain the most basic phenomena of inheritance.
http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593
One of the most impressive things about Mendel's thinking lies in the notation that he used to represent his data. Mendel's notation of a capital and a lowercase letter (Aa) for the hybrid genotype actually represented what we now know as the two alleles of one gene: A and a.
http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593
Exceptions to Simple Inheritance: It is now understood that inheriting one allele can, at times, increase the chance of inheriting another or can affect how and when a trait is expressed in an individual's phenotype.
https://answers.yahoo.com/question/index?qid=20060630013731AAibfDO
what are the fundamental units of inheritance?
Genes are the fundamental unit of inheritance. Genes are the fundamental units of inheritance.