ginlazytunba lujvo

x1 is a genetic-familial/biological/'blood' sibling of x2 by bond/tie/standard/shared genetic parent(s) x3.

Half-siblings are included; step-siblings are excluded.

In notes:

ginlazyfamti
x1 is a biological/genetic-familial/'blood' aunt/uncle of x2 by genetic-familial bond/tie/blood relation x3; x1 is a genetically and familially associated member of x2's genetic/biological parent(s)'s generation.