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Table 1 Probabilities of genotype combinations and allele sharing for several common relationships

From: Inferring relationships between pairs of individuals from locus heterozygosities

  Parent-Child Full sibs 2.nd degree Non-relatives
A) Genotype combination     
1 AA, AA pA 3 pA 2(1+pA)2/4 pA 3(1+pA)/2 pA 4
2 AA,AB 2pA 2pB pA 2pB(1+pA) pA 2pB(1+2pA) 4pA 3 pB
3 AA,BB 0 pA 2pB 2/2 pA 2pB 2 2pA 2pB 2
4 AB,AB pApB(pA+pB) pApB(2pApB+pA+pB+1)/2 pApB(4pApB+pA+pB)/2 4pA 2pB 2
5 AA,BC 0 pA 2pBpC 2pA 2pBpC 4pA 2pBpC
6 AB,AC 2pApBpC pApBpC(2pA+1) pApBpC(4pA+1) 8pA 2pBpC
7 AB,CD 0 2pApBpCpD 4pApBpCpD 8pApBpCpD
B) Number of shared alleles (Z)     
0 0 H2/8 H2/4 H2/2
1 H H(1-H/2) 3H/2-H2 2H-2H2
2 1-H 1-H(1-3H/8) 1-3H/2+3H2/4 1-2H+3H2/2
  1. A (top): probabilities of the seven possible combinations of genotypes for multi-allelic loci in pairs of individuals, conditional on their relationship, as functions of allele frequencies. B (bottom): probabilities of sharing 0, 1, or 2 alleles for diallelic loci as functions of locus heterozygosity.