def is_homozygous(self, individual=None):
        """This will give a boolean list corresponding to whether each individual
        is homozygous for the alternative allele.

        """
        if individual is not None:
            if isinstance(individual, str):
                individual = self.individuals[individual]
            alts = self.genotype[individual]
            return [sum(alts) == len(alts)] if sum(alts) > 0 else [False]
        else:
            return [sum(alts) == len(alts) if sum(alts) > 0 else False for i, alts in self.genotype.iteritems()]
This will give a boolean list corresponding to whether each individual
        is homozygous for the alternative allele.