'Mother's' in the Bible

Now Abimelech the son of Jerubbaal (Gideon) went to Shechem to his mother’s relatives, and said to them and to the whole clan of the household of his mother’s father,

So his mother’s relatives spoke all these words concerning him so that all the leaders of Shechem could hear; and their hearts were inclined to follow Abimelech, for they said, “He is our relative.”