This has some logic, but there are things wrong in it:
1-If the absence of a father would make you think you are gay, what would the absence of a mother cause?
2-Affection and sexual attraction are different things. I know people who are sexually attracted for one sex and psychologically attracted to (i. e. fell in love for) the other sex. So the book explains certain cases of psychological attraction to other men, but does not explain feeling sexual attraction to other men.