Final answer:
Haplodiploidy contributes to the altruistic behavior associated with social insects by increasing the genetic relatedness between workers and their sisters.
Step-by-step explanation:
Haplodiploidy is an unusual reproductive genetic system found in social insects like honey bees. In this system, the queen bee has two sets of chromosomes and is diploid, while the male drones have only one set of chromosomes and are haploid. Haplodiploidy contributes to the altruistic behavior associated with social insects because the workers, which are all female and have the same father but different mothers, are more closely related to each other than to their own offspring. This genetic relatedness increases the inclusive fitness of workers, meaning that helping their sisters reproduce is beneficial for passing on their own genes.