Right now the two modes of existence - nature versus nurture, ego versus love - are coexisting. Each culture and each nation has found its idiosyncratic solution. We raise and train each other to override the most disruptive instincts, like killing or stealing, but we leave a few raw elements behind to allow at least some animalistic self-expression: gladiator fights in the olden days, Toreros and bull fighting in Spain a century ago, and professional sports in today's day and age. We cannot eradicate our drives, but we can redirect and transmute them. So we encourage aggression in sports, assertion in business settings, while the sexes pursue each other in old-fashioned or new dating games. In short, each culture gives their people respectable outlets for their drives and desires, and each generation updates and modernizes this interaction.
It is hard, perhaps impossible, to say what exactly is our nature, what is given to us by our genes and parents, or the environment we operate in. What can we over-write, what should we strengthen, and what should we drop in the name of humanity and spirituality? Don't overthink it; just accept what gets your juices flowing and let life give you the symbolic outlet that works for you. The Bhagavad Gita claims that all of us have idiosyncratic drives and natures, hence, we need to be willing and eager to embrace whatever comes our Way. Arjun discovered Lord Krishna's might on the battlefield, it was his dharma (fate/nature) to fight.
A spiritual path is an idiosyncratic way to find love and co-operation in life while burning up your passions, drives and karma in whatever it is you do. The selfish gene may have created you, it may even be responsible for everything you do, but it cannot prevent you from going Home. Life wraps Itself around you and gives you the perfect outlet to burn your desires and karma in the process. No matter what story you have chosen for yourself, the choice - ego versus love - presents itself every step of the Way. You don't have to repress your nature, and you don't have to neglect your desires. Choose love but don't forget to live a little. Embrace life fully, and let Her take you Home.