Conditions experienced early in life have long-term fitness consequences. Because in most taxa the early-life environment is provided by the parents, selection should favour increased parental care. Yet, considerable variation in parental provisioning is observed within and across populations. Life history theory predicts that this variation is maintained through parental costs associated with increased offspring provisioning. Yet, the proximate mechanisms underlying such fundamental life-history trade-offs remain poorly understood. To gain insights into the constraints and trade-off that shape the evolution of life history strategies, we artificially selected Japanese quail (Coturnix japonica) for divergent maternal egg provisioning, and explored costs, benefits and constraints at the genetic, transcriptomic and phenotypic level. In this talk I will show how different family members ‘like their eggs’ and provide evidence that the immune system plays a key role in mediating the trade-off between reproductive effort and lifespan.