The following *might* be the family you are seeking. It's the only Brodie/Broadie family that has a son John who fits into your age group for John by 1870 census.
1860 Census Sullivan, Hamilton Township, Indiana Taken: 13 June 1860 217/217
Brodie, Allen25 M Farm Labor 0/50 Ind Brodie, Martha 24 F Ind Brodie, John 4 M Ind Brodie, Avenida 7/12 F Ind
1870 Census Sullivan, Hamilton Township, Indiana Taken: 25 Aug 1870 392/391
Brodie, Allen M. 37 m/w Farmer 3500/1000 Ind Brodie, Martha, 36 f/w Keeping House, Ind Brodie, John, 12 m/w, Ind Brodie, Aridla, 9 f/w, Ind Brodie, George W., 8 m/w, Ind Brodie, James, 6 m/w, Ind Brodie, Milton C., 3 m/w, Ind On this census living next door to Allen and Martha Brodie is a William Brodie age 29, born Ind and next door to William is Mary S. Brodie, age 57, born Ky.
Index to Marriage Record Sullivan County, Indiana shows: John Broadie to Eliza Daily, 7 April 1887 (Bk.8, Pg. 413)
Supplemental Marriage Transcripts Sullivan County, Indiana shows:
John Broadie, m/w, age 28 next birthday, date of marriage 7 April 1887, son of Allen Broadie and ??? McConnell (Bk.R-1, Pg. 192)