Elizabeth Skeffington - ? Parentage

At my Fathers funeral (Daniel Skeffington, 31/03/1931) Elizabeth claimed to me that she was the biological Daughter of my Father and her Mother.
That is, my Father had a sexual relationship with his Fraternal Uncle's Wife! So she is effectively my 1/2 Sister and also my Aunty!!. SCANDAL. She has not agreed to Paternity testing as @ February 2015. Daniel Skeffington (31/12/1961). This note made Feb 2015.