how to get the kinship level from estimated kinship efficient

[Yamol]

I want to know whether two people were parent-child, grandparent-grandchild.

[Yamol]

and what does a negative value (estimatd kinship coefficient) mean?

[jinzhuangdou]

For the first question, you can follow the criteria in the KING paper: Table1 (https://academic.oup.com/bioinformatics/article/26/22/2867/228512). A negative kinship value may be due to the exists of population admixture.