I assume that this book was supposed to be a sort of 'Beyond the Village of the Damned' storyline. The children are born from a mutated line of DNA from their father. This gives them strong psychic abilities, along with no empathy and a desire to harm others.
The husband of the mother of the main characters is found to be a homosexual who likes to have sex with teenage boys, and is killed off early on.
Though the gay angle is barely referenced, when it is, it done in a fairly homophobic manner. For example, when the father of the evil children is justifying why he is giving his sperm to fertilization clinics, even though he knows insanity runs in his family, he says:
'... a homosexual husband is possibly even less suitable to be a surrogate father than a murderer's son is suitable to be a donor.'