I have been researching Isaacks line in Texas for quite a few years. I found a bookcalled "The Isaacks Clan - In America and Texas" written by Mrs. J.D. Mullis, great-great-grandaughter of Mary Isaacks Parker and Matthew Parker. Mary Isaacks Parker was the daughter of Elijah Isaacks. In this book, it does state that "there is a tradition in her immediate family that some three centuries ago a family of Jews, one of whom was her ancestor, lived in Wales and married a Christian woman, on account of which his family disowned him. Whereupon he rnounced Judaism and added the "k" to his name to distinguish him from the Jews. Until a few years ago (written in 1935)when I began delving into the history of the family, I accepted this tradition as true, but from facts gleaned in the investiations, I am inclined to believe that the immigrant Samuel was either Scotch or Welsh." More on this in the book. However, in San Antonio, TX in the Institute of Texas Cultures, in the Jewish section is a plaque with the land grant issued by Stephen F. Austin.