But humans can actually make conscious choices beyond their base animal pressures. We use prophylactics even though those go against our animal pressure to procreate. We help strangers even if it won't improve our own situation and without any expectation of future reciprocation. We have to eat and sleep to live, we don't have to have children.

We also have cultural pressures, which can shape individual behavior. We could have a culture where the default is not to have kids, but that you should not have kids unless you are stable and secure enough to have then and are prepared to invest sufficiently in raising them.