Aristotle (384-322 B.C.), the Greek philosopher, thought that inheritance was not a spirit or an emotion but a physical substance coming from both parents. He also thought that the giraffe was a hybrid animal, the result of a cross between a leopard and a camel.
Why aren't there naturally occuring hybrid animals like a leopard camel cross?
Children resemble their parents.
Genes come in pairs.
Genes don't blend.
Some genes are dominant.
Genetic inheritance follows rules.
Genes are real things.
All cells arise from pre-existing cells.
Sex cells have one set of chromosomes; body cells have two.
Specialized chromosomes determine sex.
Chromosomes carry genes.
Genes get shuffled when chromosomes exchange pieces.
Evolution begins with the inheritance of gene variations.
Mendelian laws apply to human beings.
Mendelian genetics cannot fully explain human health and behavior.