Student Exploration: Mouse Genetics (One Trait) Vocabulary: allele, DNA, dominant allele, gene, genotype, heredity, heterozygous, homozygous, hybrid, inheritance, phenotype, Punnett square, recessive allele, trait Gizmo Warm-up Heredity is the passage of genetic information from parents to offspring. The rules of inheritance were discovered in the 19th century by Gregor Mendel. With the Mouse Genetics (One Trait) Gizmo™, you will study how one trait, or feature, is inherited.