Curious---Tad left or right handed?

[RJNorton]

I have looked through a lot of books, and I cannot find anywhere in the literature whether Tad was right or left-handed. I thought the answer might be in Dr. John Sotos' The Physical Lincoln, but I don't see it in there. (Dr. Sotos feels Tad's brain was not normal "but cannot say what made it so.") Personally I lean toward Tad being right-handed as when my layman's eyes look at the one authentic signature we have for Tad it looks (to me) more like the signature of a right-handed person. However, based on the research I've done so far, I don't think the answer can be determined.