Results of genetic analyses of sand tiger litters (Ct001–Ct015). N embryos is the litter size. PAC, paternal allele counts. The relationship between the hatchlings as assessed in ML-Relate is provided under the following headings: PutFS, the simulation-based probability that the alternative relationship (half-siblings) better fits the hatchling genotypes than the putative relationship of full-siblings. If this value is low then the putative relationship is most likely to be true; PutHS, the simulation-based probability that the alternative relationship (full-siblings) better fits the hatching genotypes than the putative relationship of half-siblings. n.a., test not applicable; ?, mating behaviour uncertain. ‘Behavioural polyandry’ was established by either PAC and/or when hatchlings were most likely to be half-siblings. ‘Genetic polyandry’ is established when hatchling were most likely to be half-siblings.