If this is so obvious, why can't most social movements figure it out?
538.com has this post studies indicating that parents of daughters are more likely to have "liberal" positions on laws designed to address sex discrimination, and the most recent study indicating that this generalizes out to a tendency to vote for a liberal or conservative party. the effect is particularly profound for fathers of daughters.
One would think this is obvious. Arguably, daughters give fathers a different perspective and a different stake in the outcome.
What is astounding is how progressive social organizations so often miss this point. Make a right universal and you are much more likely to get support than trying to get people to do something to benefit other people.