There are two John J. Brennans

Brennan, John J b: SEP 1867 in Heckscherville, PA d: 2 DEC 1940 in Minersville, PA 
Brennan, John J b: 1 JAN 1920 in Philadelphia, PA d: 8 AUG 1964 

1 Edward Brennan b: 1813?
  + Ann or Hannah Brennan b: 1826
    2 John J Brennan b: SEP 1867 d: 2 DEC 1940
      + Hannah Foley b: ABT 1854 d: 17 OCT 1918
        3 Edward Brennan b: 11 JUN 1893 d: 16 DEC 1972
          + Genevieve "Geneva" Leopold b: 28 SEP 1894 d: 22 NOV 1953
            4 John J Brennan b: 1 Jan 1920