Genetic inheritance boils down to three simple concepts put forth by Gregor Mendel, a humble monk and part-time scientist who founded the entire discipline of genetics:
Segregation: In diploid organisms, chromosome pairs (and their alleles) are separated into individual gametes (eggs or sperm) to transmit genetic information to offspring.
Dominance: A dominant allele completely masks the effects of a recessive allele. A dominant allele produces the same phenotype in heterozygotes and in homozygotes.
Independent assortment: Alleles on different chromosomes are distributed randomly to individual gametes.