Flesh and Blood — Graham Masterton

Out in a field, deep in the heart of Iowa hog-farming country, Terence Pearson beheads his own children, apparently without reason.

But appearances are deceptive. Terence is saving his children from a fate far worse: The Green Traveller, a strange mummer dressed in leaves, who with his companions, The Surgeon and The Witness, bring terror and pain to those who cross him. Terence knows his children are descendants of The Green Traveller, and he's returning for them ‹ the consequences of which will be devastating...

This is a complex novel which features genetics as its theme, alongside a story involving the insertion of human genes into a monstrous pig. Steeped in legends, Flesh & Blood is a fascinating read with eviscerations and decapitations aplenty.