I think the point is being missed here, they are not talking about teaching sexuality but relationships.
Children can be cruel, with anything seen as unusual, to teach children that two people of the same sex can have a loving realtionship and bring up children, just like their own parents is surely justified?
Their are gay people, those people are "out" they are going to get married and they are going to have children. I have no idea how may gay marriages there wil be, there will be.
To deny it, is archaic, like hiding your head in the sand, but people should really understand that todays 5 year olds will be FAR more accepting and understanding of gay people than todays population.
To be taught this has nothing to do with our perceptions, but theirs.
In a society that has celebrity gay couple Elton & Daveid etc, gay relationships in TV shows, Modern Family, Will & Grace and others. To not discuss and explain it to some extend is ridiculous