maternal line的用法和樣例：
例句
- Everyone has two paternal grandparents and two maternal grandparents.
每個人都有兩個屬於父系的祖父母和母系的祖父母。 - For most genes, both the maternal and paternal alleles turn on or off at the same time.Imprinting disrupts this balance.
對多數基因來說，來自父系及母系的對偶基因是同時開啟或關閉的，銘印則破壞了這種平衡。
