A novel chiral twin material, (R)-bis[5-octyloxy-2-(4-octyloxyphenoxycarbonyl)phenyl] 3-methyladipate, has been prepared, where two mesogenic parts are connected laterally by a spacer possessing a chiral centre. A weaker helical structure, in particular in the chiral smectic C (S*c) phase, was found to be induced by the laterally-connected twin material than by the analogous terminally-connected twin material. If laterally-connected chiral twin molecules prefer to stay in the smectic layer structure so that the two mesogenic parts exist in the same smectic layer, the twist interaction between adjacent layers cannot be produced by direct correlation of motion and directions of two mesogenic parts. Thus, the helical structure in the S*cphase induced by laterally-connected chiral twin molecules becomes weak. An analogous laterally-branched ‘monomeric’ compound, (S)-5-octyloxy-2-(4-octyloxyphenoxycarbonyl)phenyl 3-methyl-pentanoate, has also been prepared, and the induced helical structures compared.