There are basic gender differences in skin physiology and biochemistry. That includes hormone metabolism, hair growth, sweat rate, sebum secretion, hydration, surface pH and fat accumulation. Men have much higher levels of testosterone, which makes their skin 25 per cent thicker and behave differently to a woman’s. In women, the predominant hormone is oestrogen. Women have a higher surface pH than men, which may explain why woman have a greater tendency for dry skin.