Sibling resemblance in two manual laterality tasks.

Two tests of manual performance were adapted for French children: a dot-filling test and a tapping test. Sibling resemblance was assessed in a sample of 46 pairs of sibs. The power of intra-class correlation was estimated by a procedure of Approximate Randomization Tests. In both tests sibling resemblance was significant for overall level of motor skill (i.e. when the two hands were considered separately). Sibling resemblance was significant for degree of laterality in the dot-filling test (the closest task to writing) but not in the tapping test. The usefulness of including degree of laterality measures, in future genetic research is discussed.