Lincoln had four children, but only one of them lived on well into adulthood.
Robert Tood Lincoln grew up to become the US Secretary of War (in Garfield's administration), as well as the Ambassador to the United Kingdom.
Edward Baker Lincoln died at age 3. Many historians now believe the cause of death was thyroid cancer, but the official cause was recorded as 'chronic consumption'
William Wallace Lincoln died at age 11, most likely of Typhoid fever.
Thomas 'Tad' Lincoln died at age 18 of tuberculosis
Lincoln was reported to be close to both William and Tad, and Robert was very found of his father, who traveled much during his childhood. Lincoln was devastated by the loss of Edward and William at such young ages.
Contemporary reports have Lincoln being very lenient when it came to his children.