Is This Human Sexuality Education?

A Lexington dad became concerned when his son came home from kindergarten with a bag of books promoting diversity. The books were about foreign cultures and traditions, along with food recipes and a copy of ''Who's In a Family?" depicting different kinds of families, including same-sex couples raising children.
The bag is sent home with one student at a time, according to the co-president of the PTA. Parents received notice about the book bag at the beginning of the year and the date it is scheduled to be sent home with their child. ''The kids don't have to take the materials home," she said. ''Parents can opt out entirely or use whatever materials they want."
The dad began a series of e-mail exchanges asking school officials to notify them about discussions about same-sex marriage and other adult themes. They wanted the option to exclude their boy, from those talks. He went to the school to gain assurances and then refused to leave. He stayed at the school for more than two hours, as officials and Lexington police urged him to leave. Finally, they arrested him for trespassing.
Governor Mitt Romney said: ''Schools under our parental-notification law are required to inform parents . . . of matters relating to human sexuality that may be taught in the classroom and to allow that child to be out of the classroom for that period of the education."
Lexington School Committee chairman, said parents of older students are notified in advance when sex education will be taught. ''We don't view telling a child that there is a family out there with two mommies as teaching about homosexuality, heterosexuality, or any kind of sexuality," he said. ''We are teaching about the realities of where different children come from."
http://www.boston.com/news/local/massachusetts/articles/2005/04/29/arrested_father_had_point_to_make/

I can understand the dad's concern if they were teaching a child about homosexuality, but is this really teaching a child about homosexuality? If so, then wouldn't showing any sort of family, say one with a mom and dad be considered teaching a child about heterosexuality?