In this paper, we study 3-Thue–Morse groups, but these are the groups satisfying the semigroup identity xy2xyx2y=yx2yxy2x. We prove that if G is a 3-Thue–Morse group then 〈x,xy〉 is soluble for every x and y in G. Furthermore, if G is an Engel group without involution then we show that G is locally nilpotent.