I found this great photo on shorpy.com, then located him and his family in the 1910 census of McLennan County, Texas. According to Shorpy, he was born in 1901 and died in 1966. The 1910 census shows him living with an older brother, Walter (age 15) and their widowed mother, Fannie (age 47). Since she indicates, on the census, that she had 4 children and 4 are still living, the other two are probably married and away from home.
Fannie took in laundry and rented the house they lived in. Both boys were in school. The photo, taken in Waco, TX, November 1913, is captioned "I'm de whole show."
"The twelve year old proprietor, manager and messenger of the Club Messenger Service, 402 Austin St. The photo shows him in the heart of the Red Light district where he was delivering messages as he does several times a day. Said he knows the houses and some of the inmates. Has been doing this for 1 year, working until 9:30 p.m. Saturdays. Not so late on other nights. Makes from $6-$10 a week."
Twenty years later, in the 1930 census, Isaac was married to Viola and they had 4 children. Isaac became an automobile mechanic, he had not served in the military, and he rented their home for $9 a month! They did not have a radio (one of the questions asked on the census that year).