The people who administer the Alms Houses where I live, Henley Municipal Charities,are very strict about this (No sex please,this is Henley !) and one is not allowed to have a person of the opposite sex staying the night ! Of course, I ignore the rules as often as possible,and,indeed,it adds a certain frisson of excitement to the proceedings,knowing that one could be evicted from one's home (just let the bastards try,says I !!).I suppose in the 1600s,when the houses were built,people,assuming they made it to 60 or over (unlikely), were not expected to be capable or even desirous of carnal knowledge !