Your question is yet another example of the ignorance and fear that is displayed by people who do not want any discussion of gender or sexuality in schools .It is based on the idiotic assumption that sexual orientation and gender identity is a choice that can be manipulated by a book.
On another level, that is actually a very good question, especially coming from a cowering traditionalist snowflake you. At the same time, asking that question also exposes your narrow view of what education is and should be. While the basics of education –math, science, history. Language, literature are important, so is emotional learning- the ability to function in an increasingly diverse culture.
Those books are there to instill a positive view of people who are in some way different- people who those kids will be sure to encounter in the real world. The ways in which those kids perceive respond to those people will likely impact their success or failure in a culture where –like it or not-is increasingly rejecting bigotry and discrimination.
In addition those books that you object to also can provide a positive role model and inspiration for kids who may be questioning their sexuality or gender identity. No the books, or the discussions in the classroom will not make a kid gay or trans- thinking so is just plain stupid. But, it will give the permission to explore and express their true selves which in turn will bolster their self esteem . Those previously mentioned basics of education will do n good if a child kills themselves out of despair because they feel isolated, marginalized and alone. THAT IS WHY THOSE BOOKS ARE IMPORTANT