The woman probably has 2 motives in her statement: first is her desire to change the direction from where this prophet is trying to go, and second is a true desire to find the answer to the most controversial item of the day.

“Our fathers” is speaking of Abraham, Isaac, and Jacob.  Notice how they are set in direct opposition to the emphatic “you” later in the verse. There was great controversy between the Jews and Samaritans as to where worship should occur.  There is the potential for great error when too much emphasis is placed on how “our fathers” did things!

Further information on Samaritan thought as to the location of worship may be found in McGarvey’s commentary on this verse in The Fourfold Gospel.

Both the Samaritans and Jews recognized that God had foretold that he would indicate a special place for an altar to be built and His Presence to be found Deut 12:5-6 and both recognized that in Deut 27:4-6 God had ordered an altar to be set up on this mountain, but the Samaritan version of this verse calls the mountain “Gerizim” instead of “Ebal.”

Deuteronomy 12:5-6  But you are to seek the place the LORD your God will choose from among all your tribes to put his Name there for his dwelling. To that place you must go;  there bring your burnt offerings and sacrifices, your tithes and special gifts, what you have vowed to give and your freewill offerings, and the firstborn of your herds and flocks.

Deuteronomy 27:4-6  And when you have crossed the Jordan, set up these stones on Mount Ebal, as I command you today, and coat them with plaster.  Build there an altar to the LORD your God, an altar of stones. Do not use any iron tool upon them.  Build the altar of the LORD your God with stones from the field and offer burnt offerings on it to the LORD your God.

Since the Samaritans did not recognize any scripture apart from the Pentateuch (the first 5 books of the Old Testament — Genesis, Exodus, Leviticus, Numbers, and Deuteronomy) as being from God, they did not accept the passages which ordered Jerusalem to be the location for God’s temple. 2Chron 6:6-7, 7:12, Psa 78:68

2 Chronicles 6:6-7  But now I have chosen Jerusalem for my Name to be there, and I have chosen David to rule my people Israel.’  “My father David had it in his heart to build a temple for the Name of the LORD, the God of Israel.

2 Chronicles 7:12  the LORD appeared to him at night and said: “I have heard your prayer and have chosen this place for myself as a temple for sacrifices.

Psalms 78:68  but he chose the tribe of Judah, Mount Zion, which he loved.