The movie’s depiction of Tad Lincoln leaves something to be desired. For one thing, the real Tad suffered from a pronounced speech impediment, probably a cleft palate, that left him incapable of communicating to any but a small number of people: his parents, his older brother Robert, Elizabeth Keckley [Mary Lincoln’s seamstress] and one or two others.
In addition, in contrast to the close affectionate relationship between Tad and his father [which is accurate] the film hardly even shows Tad and his mother in the same scene.
The implication the film gives that the boy was close to his father but not to his mother was far from the truth. In point of fact Mary had already lost two of her four sons to disease and during the White House years, with Robert away at Harvard, she was especially close to Tad, for example, taking him with her on trips on a regular basis.