Honestly if kids went to single gender schools it would make them uncomfortable with the opposite sex and probably make them homosexual, whilst all gender schools have lower amounts of homosexuals (I am a christian and this is an offense to god to do same sex marriage so sorry if offended, no insults were meant). Plus kids in all gender schools are more comfortable with the other gender than same sex so there is my round 1 argument.
If kids went to same sex schools there would also be kids who won't develop a comfort level with the other gender in public because some kids will be shy towards the other gender as adults. And if that's not bad enough well there will be a lot more Sexism and Feminism and such which will cause men to put women down and act dominantly (I am a guy and know that this will also lead to men attempting to be dominant over other men). Along with the insults and things THERE WILL BE A LITERAL CIVIL WAR IN AMERICA BETWEEN MEN AND WOMEN IF THIS HAPPENS. so there is round 2.