Reply to Alixz and others:
There is today an unconscious/subconscious impression abroad that the "sexual" self is, in great measure, the true self as opposed to the public, more inhibited self. Hence the preoccupation with people's sex lives, sexual preferences and habits. In the past the sexuality of Royalty was of international importance for dynastic, religious and territorial reasons. Whether they could produce heirs and thus continue alliances could - and did - affect the destinies of large communities. The Austrian Empire was built up through judicious marriages. The failure of a line could - and often did - lead to war.
The interest in the private lives of royalty today is, in some ways, a relic of this former fact of existence. The genetic inheritance of Royalty has recently taken on a new significance in the ongoing debate between "nature" and "nurture" in assessing behaviour - Royal Families having better access to historical records than most people and which tend to go much further back into the past. Repeating patterns of behavious can then be observed and analysed.
With regard to elected authorities and officials, their vulnerability is only too apparent. I remind posters of politicians both recent and in the not-so-distant past whose careers were damaged or destroyed by sexual 'misconduct'.
It should not matter in the 21st century, but it does. For a historian this aspect of an individual's life canot be ignored as it was so important to that individual in life and may well have affected their actions and policies. Demographers are also preoccupied with sexual habits, so are economists, anthropologists and so on.