No one really knows whether to give credence to Waddell's idea and it has become out of fashion because the Nazi's used the notion to fashion their silly beliefs in racial superiority as was fashionable over 150 years ago.
We all know racism is just plain stupid and theories supporting it are nonsensical! There is no superiority of any particular race or people. Nature has established the importance of mixing races to produce healthier people. It's a no brainer that the symbolism of the Nazi regime was a monstrous development and blemish on logical thought.
Whether there is a link between early people's near south eastern Turkey and Scotland is a fascinating question? We only know that the most hated symbol of the modern world was once a symbol of respect many thousands of years before!