1to pursue sth back to its origins
2to trace back to the source
3to get to the bottom of sth
Examples
ruò若zhuī gēn sù yuán追根溯源，jué dà duō shù绝大多数měi guó美国rén人dōu都shì是yí mín移民。
若追根溯源，绝大多数美国人都是移民。
Most Americans are descended from immigrants.
如果追根溯源的话，绝大多数美国人都是移民。
Most Americans are descended from immigrants.