In the first progeny generation (G0 in 2004), there are unrelated pairs of individuals (2θ = 0), half-sibs (2θ = 0.25), and full sibs or parent-offspring (2θ = 0.5, Figure 4.4). By the later generations, there are more complex relationships because of distant common ancestors. For example, individuals 211 and 322 have a small relationship (2θ = 0.0625) because of common ancestry in preceding generations (Figure 4.4).