x1 is a genetic-familial/'blood' descendant of x2 by bond/tie/relation/of degree x3.
x1 must be the genetic offspring of x2 or the genetic offspring of someone who is also a ginlazyseldze of x2; trivially, one may consider x2 to be a ginlazydze of themself (x2), and possibly/probably others. See also: kraune, kloje, tseingu, dzena. This is more specific than seldze (x3 is much narrower). This word is equivalent to "se ginlazdze".