Biased sample. There are many confounding factors why if you cannot tell the difference, it is likely your family can’t either.

I do like the idea of testing my wine drinking friends, who are definitely not snobs. I would bet money they would mostly pick the difference between a normal: Oaked Chardonnay, Reisling, Savignon Blanc, and Cabernet Savignon. I suspect the red wine drinkers could tell some of the red wine varietals too (I would struggle there).