Coefficient of Inbreeding is in General Things.
Coefficient of Inbreeding describes the probability that an individual will have homozygous genes ie the gene will have the same two alleles. For each generation the probability reduces by a factor of four:
25%: a child of siblings, or father and daughter, or mother and son.
12.5%: a child of half-siblings, or double first cousins, or uncle and niece, or aunt and nephew
6.25%: a child of first cousins.
1.5625%: a child of second cousins.