 One important fact to notice is that the colony is one large family: typically, the workers are sisters—daughters of the queen. Return to the idea of “selfish genes” described above: what ultimately increases an allele’s representation in the gene pool is its having some phenotypic effect that causes copies of that allele to be in more organisms in succeeding generations. That normally happens when the phenotypic effect causes the organism to have greater reproductive success, but it can equally happen if it causes the organism’s close kin to have greater reproductive success: for close kin are likely to carry copies of that same allele, which means that greater reproductive success for kin likewise propagates copies of the allele. So while an allele that causes an organism to engage in sex more often may thereby spread, so might an allele that causes an organism to help a sibling to reproduce (as by aiding survival); either way, that allele will be helping to propagate copies of itself in the next generation, which in turn means that the helping behavior it causes will likewise spread over time (Dawkins 1989, 171–77).