Geni probably has a dozen or more genealogies of John Brown (1620-1690) of Milford and Newark, which give his father as Francis Brown of New Haven (1610-?). They are clearly two different people, and Jacobson, eminent genealogist of New Haven, long ago established Francis Brown's basic family and statistics. (See Ancient Families of New Haven.) Francis did have a John, but about the same time that the Milford John Brown had his son, John, Jr. in Milford.
I realize you didn't make the mistake, but you leave no place for me to reply when I get a message saying that John Brown, son of Francis, is my cousin or my x-times great grandfather.
At least give me a chance to correct it.
It is probable, but not certain, that John Brown of Milford and Newark, was christened in St. Mary's, Hitchin, Hertfordshire, in 1620. That is where his wife, Mary Burwell, was born also.