From the parental perspective, each individual's overall reproductive effort is a combination of mating effort and parental effort or investment. There are numerous factors that can have an impact on the amount of parental resources invested in any particular child. The potential for conflict exists between parents over how much parental investment each should give to their shared genetic offspring. Offspring compete amongst themselves for access to parental resources. Parent‐offspring conflict can arise because some actions that advance the fitness of an offspring can potentially reduce the lifetime success of the parent and just as some actions that benefit parental fitness can reduce the lifetime fitness of a particular offspring. Natural selection has shaped strategies for sibling competition just as it shaped mechanisms for discriminative parental solicitude. Many factors play a role in the approach individual siblings may take, but two are of particular interest: birth order and birth spacing.