Gender definitions are based on a combination of hormonally-driven physiological traits and cultural expectations. Physiological traits are world-wide constants: males are generally physically stronger, less emotive, more aggressive, etc.
Females are generally physically smaller, more cooperatively-oriented, less muscular, more overtly emotional, etc. Across the world and over the centuries definitions of what constitutes expected and valued masculine and feminine behaviors have varied. By and large throughout time heavy labor such as is required for farming and hunting has been part of the masculine definition while cooking, food preservation and performing the labor necessary to keep the family and home functioning have been part of the definition of feminine behavior.
There are, however, anomalies that have occurred in some cultures such as the phenomenon of women warriors that have been found in central Asia. Some cultures (such as European/American/middle eastern cultures), often religion-driven, have had extremely narrow definitions of what is considered acceptable masculine/feminine behavior as determined by genitalia, while others are more flexible allowing individuals to follow their own internal and emotional dictates and having languages that recognize more than two gender labels.