The major pulls behind the minds of parents for sending the child to single -sex school is just to stop their child to seek out the opposite sex,to minimise their contact with them, and even to stop them from indulging themselves in shameful stuff.
The negative point in this context is that it is but obvious of human nature to be curious and to explore the things that are denied to them.So by sending their children to single sex school,parents themselves provoke their children to be curious about the opposite sex.
Sending one's child to a single sex school doesn't stop them seeking other sex, there are other options open to them like tutions,neighbourhood,friends of friends etc.

While inversely sending one's child in co-ed ambience will give them exposure to the opp.sex from the outset.
So in future the same child have to go in corporate world so the atmosphere there will not be run of the mill for child.
Surveys clearly reveals that chances of the child being carried away by the opp sex are 45% more in case of the
child being brought up in single sex environment.