Inbreeding
From Genetics Wiki
The concept of inbreeding, mating among relatives, in genetics can get confusing because there are different defintions of inbreeding. One definition is in a pedigree sense, mating among close relative with a known genetic relationship. This can be quantified by the degree of predicted autozygosity in a pedigree and quantified by [math]F[/math]. To avoid confusion with other definitions of [math]F[/math] I like to symbolize it as [math]F_{pedigree}[/math] or simply [math]F_{PED}[/math]. Another definition of inbreeding is in a Hardy–Weinberg sense, mating among relatives in a population more often than by chance. This population-wide definition is quantified by [math]F_{IS}[/math].