Excuse us, ladies, but you can't drink as much as men. This is not some male conspiracy, it's a biological fact!
Women have fewer bodily fluids than men, so the concentration of alcohol in their blood (BAC, Blood alcohol concentration) is proportionally higher. So, if a woman who weighs 60 kilos drinks a double gin, then a man of the same size will need to drink a triple gin to get his blood alcohol to the same level.
There is some evidence that women have fewer amounts of the ADH enzyme (which is responsible for the breakdown of alcohol in the liver and stomach walls) and this may play a role in higher BAC levels.