Supplementary Table S3 The probabilities that each of the 11 possible matings will give rise to offspring of each phenogenotype in the population-genetic model (Model 1) with oblique/horizontal cultural transmission of paternity beliefs. The rows r1-r11 show all permitted genotype matings. (Note that not all combinations are possible given our assumptions, e.g. two m individuals cannot be monogamous. Only the permitted matings are shown in the table.) Column c0 shows the frequency of each genotype mating under the assumption of random mating, where x1, x2, x3, x4 are the frequencies of MBp, MBs, mBp and mBs in males and y1, y2, y3 and y4 the equivalent for females. Columns c1-c14 show the probabilities that the offspring of each mating will adopt each phenogenotype, given haploid genetic inheritance and oblique/horizontal cultural transmission (where z is the frequency of Bp in the previous generation, i.e. z=x1+y1+x3+y3 and 1-z is the frequency of Bs). The bias b1 promotes Bs in the offspring of M matings, and the bias b2 promotes Bp in the offspring of m matings. See Methods for further details. OFFSPRING MATING FREQ Monogamy Polygyny Polyandry Polygynandry c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 c13 Male1 Female1 Male2 Female2 MBpp MBsp MBpp MBsp mBpp mBsp MBpp MBsp mBpp mBsp MBpp MBsp mBpp r1 M M (x1+x2) (y1+y2) z - b1 z 1-z+b1 z r2 m M M (x3+x4)(y1+y2) 0.5 z 0.5 (1-z) 0.5 z 0.5 (1-z) (y1+y2) r3 M m M (x1+x2) (y3+y4) 0.5 z 0.5 (1-z) 0.5 z 0.5 (1-z) (x1+x2) r4 M m m M (x1+x2) (y3+y4) 3/8 z 3/8 (1-z)5/8 z (x3+x4) (y1+y2) r5 M m m m (x1+x2) (y3+y4) 1/8 z 1/8 (1-z)7/8 z (x3+x4) (y3+y4) r6 m M M m (x3+x4) (y1+y2) 3/8 z 3/8 (1-z)5/8 z (x1+x2) (y3+y4) r7 m M m m (x3+x4) (y1+y2) 1/8 z 1/8 (1-z)7/8 z (x3+x4) (y3+y4) r8 m m M M (x3+x4) (y3+y4) 0.5 z 0.5 (1-z) 0.5 z (x1+x2) (y1+y2) r9 m m M m (x3+x4) (y3+y4) 1/8 z 1/8 (1-z)7/8 z (x1+x2) (y3+y4) r10 m m m M (x3+x4) (y3+y4) 1/4 z 1/4 (1-z)3/4 z (x3+x4) (y1+y2) r11 m m m m (x3+x4) (y3+y4) z+b2(1-z) (x3+x4) (y3+y4) c14 mBsp 5/8 (1-z) 7/8 (1-z) 5/8 (1-z) 7/8 (1-z) 0.5 (1-z) 7/8 (1-z) 3/4 (1-z) 1-z-b2(1z)