It starts right from the time the child is born. Blue for boys and pink for girls. Growing up, telling the boys not to cry because men dont cry and asking the girls to be polite because apparently girls are delicate. 
It seeps in drop by drop. Through the environment a child is in. The society looking at the father’s work as the “manly” one while the mother’s as the “homely” one. 
The tv ads.. reinstating what a child sees around. The movies.. with dialogues like “hansi to phasi” or “ladki ki na mei bhi haan hai”. 
The objectification, the sexist jokes, the inequality, the supposed “male domination “. 
The subtle entry of an 8 year old brother who walks to the shop down the street with his sister. To “protect” her. The “protection” provided here would not be by the virtue of his strength but would wholly depend on the virtue of his gender, accepted by the society. 
It grows. Builds up piece by piece. And it solidifies taking a shape. 
Takes the shape of a mentality. 
Looking at women as objects, as inferiors, as helpless, as second class citizens. 
Who are the rapists and the molesters roaming around in the society? Are they men with horns or wings? How do we identify such creeps? 
Ummm.. well.. we cant. Because they are a part of us. But, what we can do is, identify our own actions, our own mentality. Be more open minded, teach the boys that they are not here to protect their sisters or mothers or wives. They are here to coexist. Women dont need help. Women dont need men to walk around freely. Women dont need men for protection. 
We form the society. We encourage, accept, implement double standards. We don’t believe in equality. And that one faction, that one small thought at the back of our minds laughing at sexist jokes, accepting that women need help and considering women not equal to the other sex collectively takes the shape of that man who soaked all those things that he saw as a child, things that we showed him, the things he later believed as a man. 
The onus is on us.