Sex is a biological term and gender is depended on the roles performed by an individual. In our society it is mandatory for a man or woman to behave and develop sexual preference for its opposite gender and this conservative thought process had strongly held the base of defining a sexual acts which is intended to happen between a male and female only.
However, this is not something defined by nature but by individual likeliness. This is the reason why even after being a male by sex, a male by gender can have likeliness for another male. This is something which cannot be bounded by social and cultural belief even after being into it for years.
It is because of what we called Greenhouse Gases. Greenhouse Gases absorbs the heat of the sun and brings it out to the earth. The heat of the sun travels 8 minutes and 20 seconds.