Re: Having a sister ............
I think having any positive female influence in a man's life, will in some shape or form his life. For example, my cousins do not have a sister (4 boys), however, they are four of the most respectable and polite members of the male species I have met. They have always been protective of me and have said numerous times before acting they consider how it would be if the person in question was their mother or me for example.
I do think women can be calming influences.