uncle's son
Report Abuse. 1  Grandparent, Grandparent's sibling=your great Uncle be certain, be certain sibling (Aunt or Uncle), great-uncle's son (1st cousin on your be certain) You, great-uncle's son daughter (2d cousin to you) Your great-uncle's son is a (first) cousin on your be certain. You and your great-uncle's son are first cousins, as quickly as bumped off.